With the transfer deadline fast approaching, time is short for clubs to strengthen their squads before the window shuts until January.
Who are the players who will be prime targets and what are the chances of the big deals being done?
Here are some of the deals that could define the transfer deadline, which for most of Europe was on Monday but for English clubs is at 18:00 BST on Tuesday.
John Stones (Everton)
IN THE FRAME? Chelsea
WHY? Chelsea's defence suddenly looks in need of a refit with John Terry 35 later this year, Gary Cahill's form indifferent and Branislav Ivanovic looking vulnerable.
In Stones, Chelsea believed they would be getting one of England's most accomplished rising stars, an asset for now and the next decade. This would not just be an instant upgrade but a long-term investment.
HOW MUCH WILL HE COST? Priceless say Everton
WHERE WILL HE FIT IN? Jose Mourinho's plan was for England defender Stones, 21, to be the long-term replacement for captain Terry, initially acting as his partner before taking on a more significant role later.
Stones would add pace and ability on the ball to a Chelsea defence that has shown signs of fraying at the edges this season. He has figured at right-back for Everton, and indeed England on occasions, so he could initially put pressure on Ivanovic, but this is not where his future lies.
He is a young player of great discipline, with only one yellow card in the Premier League last season - although he was sent off against Young Boys in the Europa League. Stones had an almost 90% accuracy rate with his passing and an 81.82% success rate in the tackle.
WILL IT HAPPEN? Chelsea have pursued this deal vigorously since making a £20m offer more than a month ago but Everton have simply refused to budge, turning down a succession of offers up to £30m while insisting this deal will not happen.
Manager Roberto Martinez said: "Sometimes money can't buy everything and that is going to be a very strong statement at Everton."
These are not words that are usually recognised by Chelsea and Roman Abramovich but Everton have said them loud and clear.
VERDICT: Everton have made a major statement here and the credibility of manager Roberto Martinez and chairman Bill Kenwright is on the line. No deal.
Edinson Cavani (Paris St-Germain)
IN THE FRAME? Arsenal
WHY? Arsenal desperately need a striker to augment the brilliance of Alexis Sanchez. Olivier Giroud is serviceable and effective but the suspicion remains he is still just short of the very top class.
Gunners boss Arsene Wenger had a perfect platform to build from after a superb run towards the end of last season which saw them retain the FA Cup - but even he admits their start to the season has been "very average".
Cavani is the sort of high-profile figure that will not only ease the frustrations of supporters who want to see Arsenal move into the elite market again, but also the sort of striker who might just give them that added dimension to mount a serious title challenge.
HOW MUCH WILL HE COST? £50m
WHERE WILL HE FIT IN? The 28-year-old has a consistent history of goalscoring, with 78 in 104 appearances for Napoli and 34 in 66 for PSG.
He could be the spearhead of Arsenal's attack with his powerful frame and allow the likes of Sanchez, Theo Walcott, Alex Oxlade-Chamberlain, Mesut Ozil and Jack Wilshere to work around him, depending on what the occasion demands.
WILL IT HAPPEN? Wenger has been dropping subtle hints that he is up to something in the transfer market - and proved he can pull off the spectacular late deal by luring Ozil from Real Madrid for £42.4m on deadline day two years ago.
VERDICT: Will be a spectacular coup if Arsenal can pull it off because PSG will drive a fierce bargain - but the Gunners are up to something.
Saido Berahino (West Bromwich Albion)
IN THE FRAME? Tottenham
WHY? Spurs' early season performances have pointed to a very obvious weakness - a lack of firepower and a shortage of support for Harry Kane. The plan to reunite him with his England Under-21 colleague chimes as an obvious attempt to remedy the problem.
HOW MUCH WILL HE COST? £25m
WHERE WILL HE FIT IN? Spurs manager Mauricio Pochettino sees him as a neat fit alongside Kane and the pair would dovetail well, with Berahino's pace giving Spurs an added extra while both can drop deep and be dangerous.
Berahino was key to West Brom's survival last season, with 14 Premier League goals, and the belief is he will only improve, hence Pochettino's desire to bring him to White Hart Lane.
WILL IT HAPPEN? Berahino and Spurs clearly want it to but there has been one rejected transfer request and two rejected offers. West Brom chairman Jeremy Peace is as tough a negotiator as they come so it will be intriguing to see how any further talks pan out with the equally hardline Daniel Levy at Spurs.
VERDICT: Down to the wire on this one and still the chance Spurs may make one last bid - but what Jeremy Peace says, Jeremy Peace usually means.
Charlie Austin (Queens Park Rangers)
IN THE FRAME? Crystal Palace, Leicester City, Newcastle United, Norwich City, Everton, West Brom
WHY? Here is a player who proved himself in a relegated side at QPR last season, performing well enough to win an England call-up. Deserves a bigger stage than the Championship.
HOW MUCH WILL HE COST? £15m
WHERE WILL HE FIT IN? Given Austin's attitude he will fit in anywhere. He is an archetypal hard-working striker, ready to go looking for work for the team, strong in the air and with proven ability in front of goal with 18 goals - five headers - in the league last season.
All the clubs interested want a spearhead who will give them goals. He fits the bill.
WILL IT HAPPEN? A major surprise that it has not happened already but QPR are determined to get £15m, which proved too much for Newcastle, while Leicester's £12m bid was rejected.
West Ham co-owner David Sullivan voiced public doubts about the condition of Austin's knee. The player responded emphatically and can also point to the fact he played 35 league games last season - hardly the tally of someone with a fitness problem.
He will continue to tempt clubs right up to deadline - and one will surely bite.
VERDICT: Got to be worth a punt given his record and price tag - expect one of the chasing pack to be tempted into trying to do a deal with QPR before deadline.
Paul Pogba (Juventus)
IN THE FRAME? Chelsea
WHY? The young France midfielder Sir Alex Ferguson allowed to slip through his fingers at Manchester United is now one of the world's most coveted talents and would cost a British record fee, eclipsing the £59.7m United paid Real Madrid for Angel Di Maria, to bring him to Stamford Bridge.
At just 22, he has a glittering career in front of him and would add energy and quality to any midfield.
HOW MUCH? £70m
WHERE WILL HE FIT IN? Chelsea's midfield has not looked balanced this season, with Cesc Fabregas's ability as a defensive player exposed at Manchester City and Nemanja Matic not showing his old authority yet as a shield for a vulnerable defence.
Pogba's introduction would give the midfield mobility, power and skill in abundance and pose problems for teams all over the pitch. It would ease the load on Fabregas and perhaps give even more freedom to the likes of Eden Hazard. It would be a wonderful signing.
WILL IT HAPPEN? Juventus know what an asset they have in Pogba, hence their ability to apply a prohibitive price and drive a hard bargain - but there have been signs in recent days that 'The Old Lady' may be willing to do a deal at that record price.
VERDICT: This deal will take some doing but Chelsea have the ambition and finance to do it. It would be one of the deals of the window should they pull it off.
Ezequiel Garay (Zenit St Petersburg)
IN THE FRAME? Chelsea
WHY? With the trail to John Stones going cold, Mourinho may still seek central defensive reinforcements before the close of the transfer window. It is clear he sees strengthening in that department as a priority - so does he act now or wait until January, or more likely next summer, to try for Stones again?
HOW MUCH WILL HE COST? £15m
WHERE WILL HE FIT IN? Experienced, tough Argentine defender who has long been linked with Manchester United. Will be a reliable back-up for Terry and Cahill - lack of express pace may be a problem.
Experience will not be, having been a permanent fixture in Argentina's team in their run to the 2014 World Cup final, which they lost to Germany.
WILL IT HAPPEN? Depends on the stance Mourinho takes, whether he still wants additions now or if he plays a long game and returns for Stones further down the line.
VERDICT: Outside chance of a deal as a fallback option to Stones. Would be a solid addition but not the long-term solution Mourinho had in mind until he ran into Everton's refusal to do a deal.
Virgil van Dijk (Celtic)
IN THE FRAME? Southampton, Everton
WHY? The elegant Dutch defender has made his name as one of the stars of the Scottish Premier League since moving to Celtic from Groningen for £2.6m in June 2013. He has suggested he may be a prime asset south of the border.
HOW MUCH WILL HE COST? £10m
WHERE WILL HE FIT IN? Southampton manager Ronald Koeman is a big admirer of his fellow countryman and despite having Jose Fonte and Steven Caulker, believes Van Dijk would add quality and composure to his side. The big question is can the 24-year-old make the transition to the Premier League?
He played his part in securing 21 clean sheets in 35 league games for Celtic last season - but has been exposed as Celtic have stepped up into European competition, including the four goals they conceded as they went out to Malmo in the Champions League group stage. It means he carries the air of the unproven.
WILL IT HAPPEN? Every chance that he will make the move now Celtic are out of the Champions League - and Southampton have been leading the way.
VERDICT: Expect him to leave - but a gamble for anyone willing to pay £8-10m.
Adnan Januzaj (Manchester United)
IN THE FRAME? West Ham United, Sunderland, Everton
WHY? Gifted young Belgian who has struggled to make an impact under Louis van Gaal but is still held in high regard at Manchester United, scoring the winning goal at Aston Villa earlier this season. One for the future who may be allowed out to aid his development - but only if United sign another striker.
HOW MUCH WILL HE COST? Loan deal only.
WHERE WILL HE FIT IN? The 20-year-old offers real versatility in attack, where he can play wide or behind the striker but needs to improve his goal tally after not scoring in 18 league appearances last season.
Can see the appeal for West Ham United but do Everton have too many players of a similar type?
WILL IT HAPPEN? An outside bet as he has been getting game time this season - but Van Gaal may be tempted to send him out if he can bring in another striker.
VERDICT: Could be a late deal if Manchester United can bring in another striker.
Victor Wanyama (Southampton)
IN THE FRAME? Tottenham
WHY? Tottenham's indifferent start to the season has underscored the need for manager Mauricio Pochettino to bring in reinforcements. Wanyama would not only provide power and drive in midfield but also act as a defensive shield.
HOW MUCH WILL HE COST? £20m
WHERE WILL HE FIT IN? Wanyama proved, first at Celtic, then at Southampton what an effective player he can be.
An imposing figure who is good on the ball, he can provide the reliable base and perfect foil to the developing young talents of Nabil Bentaleb and Ryan Mason. His ability as a holding midfield player and formidable presence proved crucial as Southampton enjoyed two excellent Premier League seasons.
In 32 Premier League games for Saints last season he scored three goals but this is clearly not his strength. This comes with his reliability in possession and in the tackle, with an 84.13% passing accuracy and 83.87% success rate in the tackle.
WILL IT HAPPEN? Southampton insist there will be no more sales to follow the likes of Morgan Schneiderlin and Nathaniel Clyne - and also insist there was nothing sinister in the stomach infection which has sidelined him.
What is not in question is that the player appears to be unsettled, Southampton manager Ronald Koeman explaining he did not figure against Norwich because he was not "mentally and physically good enough to play".
Given that former Saints boss Pochettino is now in charge at Spurs, it may add another layer of determination from Southampton to ensure the deal does not progress.
VERDICT: Expect Spurs to push this one - and deadline day would not be complete with some activity at White Hart Lane in the closing moments. Recent events surrounding Wanyama suggest the player would like the move too.