Real Madrid, Barcelona, Juventus, PSG: How could Europe's top sides look in 2019-20?
There have been plenty of rebuilding jobs across Europe's top clubs this season - with at least two footballing institutions being broken up.
It can be impossible to keep on top of everyone's signings so BBC Sport has had a look at what the continent's best teams have been up to - and how they could line up on the opening day.
This could all change between now and the start of the season - with the deadline for everyone, except English clubs, on Monday, 2 September.
End of an era at Atletico Madrid
It is the end of an era at Atletico Madrid as La Liga's meanest defence for six of the past seven seasons has been broken up. Stalwarts Diego Godin, Filipe Luis and Juanfran have all left on free transfers after eight years together (one Luis season at Chelsea aside).
Lucas Hernandez, who overtook Luis at left-back, is also going - to Bayern Munich for £68m.
Atletico have had a complete overhaul of the squad, with a reported £220m spent on new faces - and about £280m recouped by sales.
Five or six debuts are likely on the opening day - including three new faces alongside Uruguay international Jose Gimenez at the back. Kieran Trippier was a surprise signing from Tottenham at right-back, young Brazilian Renan Lodi is their only option on the left - with ex-Espanyol man Mario Hermoso and Felipe from Porto competing to be alongside Gimenez.
Atletico replaced the sixth most expensive player in history with the fifth. Antoine Griezmann left to go to Barcelona for 120m euros (£107m) - although Atleti want more in a legal dispute. They spent all of that money - and another £5m - to sign Benfica teenager Joao Felix, who has only won one cap for Portugal.
In midfield Rodri left to become Manchester City's £62.8m record signing, with Marcos Llorente, arriving from Real Madrid, likely to take his place.
In: Defenders Kieran Trippier (Tottenham), Renan Lodi (Athletico Paranaense), Felipe (Porto), Mario Hermoso (Espanyol), midfielders Marcos Llorente (Real Madrid), Hector Herrera (Porto), forwards Joao Felix, Ivan Saponjic (both Benfica)
Out: Defenders Lucas Hernandez (Bayern Munich), Diego Godin (Inter Milan), Filipe Luis (Flamengo), Juanfran (free agent), midfielder Rodri (Manchester City), Gelson Martins (Monaco), Antoine Griezmann (Barcelona)
Sarri's Juventus era begins with significant changes
Not to the same extent as Atletico Madrid, but another famous defence is changing at Maurizio Sarri's Juventus. Their famous 'BBC' backline of Andrea Barzagli, Leonardo Bonucci and Giorgio Chiellini are no more.
Barzagli has retired after 281 appearances for the club, while Sarri is unlikely to play the wing-back formation of the past, meaning there is only space for one of Bonucci or £67.5m signing from Ajax Matthijs de Ligt next to captain Chiellini.
De Ligt is one of three young defenders to come in, with Luca Pellegrini, a recruit from Roma, likely to challenge Alex Sandro at left-back.
The kings of the free transfer have done it again with club legend Gianluigi Buffon returning as well as experienced midfielders Aaron Ramsey and Adrien Rabiot.
They have had to pay Wales' Ramsey £400,000 a week to make the move from Arsenal, with Rabiot - who was frozen out by Paris St-Germain after failing to sign a new deal - likely to be on big wages too.
A surprising move saw Rabiot's team-mate of last season, Buffon, return to Juventus after one season away. He needs to make eight more Serie A appearances to break Paolo Maldini's record of 647 but he will face a battle to take the place of Wojciech Szczesny, who was his long-term replacement 12 months ago.
In: Goalkeeper Gianluigi Buffon (Paris St-Germain), defenders Matthijs de Ligt (Ajax), Luca Pellegrini (Roma), Merih Demiral (Sassuolo), midfielders Aaron Ramsey (Arsenal), Adrien Rabiot (Paris St-Germain)
Out: Defenders Leonardo Spinazzola (Roma), Andrea Barzagli (retired), midfielder Stefano Sturaro (Genoa)
How will Bayern adapt without 'Robbery'?
No more Franck Ribery and Arjen Robben. Robben and Ribery. 'Robbery'. The duo played on opposite wings for Bayern for a decade, injuries aside. Ribery won nine Bundesliga titles in 12 seasons, with Robben managing eight in 10. The pair scored a combined 185 league goals before leaving at the end of their contracts this summer.
Kingsley Coman and Serge Gnabry are able replacements, but Bayern have publicly declared their interest in Manchester City and Germany winger Leroy Sane.
Bayern still have rebuilding to do. They have signed France's two World Cup-winning full-backs in Lucas Hernandez and Benjamin Pavard for about £100m in total, with both deals confirmed before the end of last season. But highly-rated young German forward Jann-Fiete Arp is their only other recruit so far.
To fit their defenders in, Bayern manager Niko Kovac will need to make tough choices. With one of the best right-backs in the world in Joshua Kimmich, Pavard is more likely to play in the centre next to Niklas Sule. They have already sold Mats Hummels to Borussia Dortmund, with Jerome Boateng likely to leave too.
Could Hernandez's £68m move spell the end of Austrian left-back David Alaba or will Kovac find a way to squeeze them both in?
Attacking midfielder James Rodriguez returned to Real Madrid at the end of his loan spell.
In: Defenders Lucas Hernandez (Atletico Madrid), Benjamin Pavard (Stuttgart), forward Jann-Fiete Arp (Hamburg)
Out: Defenders Mats Hummels (Borussia Dortmund), Rafinha (Flamengo), Franck Ribery (released), Arjen Robben (retired)
A summer without a superstar signing at PSG - so far
There has been no major overhaul at PSG, with three good - albeit not superstar - signings for the first team and several fringe players leaving.
In an uncharacteristically sensible signing, solid central midfielder Ander Herrera comes in on a free transfer from Manchester United. Centre-back Marquinhos has had to play the role sometimes in the past - because of PSG's love of filling their squad with attacking talent.
They do actually have plenty of choice in central defence with Abdou Diallo coming in from Borussia Dortmund to compete for spaces with Marquinhos, captain Thiago Silva, France's Presnel Kimpembe and Germany international Thilo Kehrer.
Their third signing, talented Sevilla playmaker Pablo Sarabia, faces a battle with Angel di Maria for a spot alongside Neymar and Kylian Mbappe in behind Edinson Cavani.
Of course if Neymar - a reported Barcelona and Real Madrid target - leaves, then all bets are off and who knows who PSG might end up signing.
In: Defender Abdou Diallo (Borussia Dortmund), midfielders Ander Herrera (Man Utd), Pablo Sarabia (Sevilla)
Out: Goalkeeper Gianluigi Buffon (Juventus), defender Dani Alves (released), midfielders Moussa Diaby (Bayer Leverkusen), Christopher Nkunku (RB Leipzig), Adrien Rabiot (Juventus)
How do Barcelona integrate Griezmann?
Barcelona have made two big signings - Antoine Griezmann and Frenkie de Jong, but other than that it has been changing back-up keepers and letting fringe players leave.
De Jong - one of the stars of Ajax's Champions League semi-final run - has moved for £67m and is seen as the long-term replacement for holding midfielder Sergio Busquets. But with Busquets only recently turning 31, it is likely Ernesto Valverde will find a way to fit both of them in for a while.
Barcelona's shape and front line are up for debate. Valverde has played a 4-4-2 and 4-3-3 formation, but he might need the latter if he wants to fit £107m former Atletico Madrid forward Griezmann into his current team.
Griezmann and new team-mate Lionel Messi are the only two players to score 10 or more goals in each of the past seven La Liga seasons. A 4-4-2 would mean 32-year-old Luis Suarez could lose his place and even a 4-3-3 would see Griezmann having to play on the wing instead of the centre.
If Neymar were to join from PSG, then that would complicate things further.
Their other transfer just affects who sits on the bench behind Marc-Andre ter Stegen and maybe plays in cups. They have swapped goalkeepers with Valencia - with Neto joining and Jasper Cillessen leaving.
In: Goalkeeper Neto (Valencia), midfielder Frenkie de Jong (Ajax), forward Antoine Griezmann (Atletico Madrid)
Out: Goalkeeper Jasper Cillessen (Valencia), midfielder Denis Suarez (Celta Vigo)
Zidane finally gets his wish at Real Madrid
Zinedine Zidane wanted a refreshed Real Madrid team this season - and he has got his wish. The French manager left at the end of 2017-18 because he felt the club needed big changes and president Florentino Perez did not. Two managers in 10 months later and Perez finally agreed, bringing Zidane back.
The big recruit has been Eden Hazard, whose move from Chelsea could end up costing £150m. That gives Gareth Bale even less chance of starting and he is expected to leave for China.
They have also signed a new striker in Luka Jovic, who scored 27 goals in 48 games for Eintracht Frankfurt last season, including 10 in the Europa League. He will face a battle with Real's sixth all-time top scorer Karim Benzema for a spot up front.
If he does take Benzema's place that would leave nobody left in the XI from the old 'BBC' frontline including Cristiano Ronaldo which won four Champions Leagues in five years.
Aside from Hazard, their other new signings are not household names across Europe - but Jovic, young defenders Eder Militao and Ferland Mendy and Brazilian midfielder Rodrygo cost a combined £193m (217m euros).
It is possible all five of the new signings could start on the opening day, or it could be only Hazard.
In: Defenders Eder Militao (Porto), Ferland Mendy (Lyon), midfielder Rodrygo (Santos), forwards Eden Hazard (Chelsea), Luka Jovic (Eintracht Frankfurt)
Out: Defenders Theo Hernandez (AC Milan), Sergio Reguilon (Sevilla, loan), midfielders Mateo Kovacic (Chelsea), Marcos Llorente (Atletico Madrid), Dani Ceballos (Arsenal, loan)
*Selected transfers for each team only