|US Open, Flushing Meadows, New York|
|Dates: 25 August-8 SeptemberCoverage: Live radio and text commentary on Andy Murray's matches, plus commentary every day from 18:00 or 18:30 BST on BBC Radio 5 live sports extra|
Andy Murray says he's given a lot of thought to what went wrong in his listless defeat to Grigor Dimitrov in July's Wimbledon quarter-final.
Even though he prefers to keep his conclusions to himself, the next few days will indicate whether he has found the key to start beating other members of the sport's elite once again.
Victory over Jo-Wilfried Tsonga at the US Open on Monday would be Murray's first against a top-10 player since winning last year's Wimbledon. It is also very likely to set up a quarter-final with world number one Novak Djokovic.
"It's not really about how you play," he told BBC Sport after his third round win over Andrey Kuznetsov.
"Sometimes you can play really good tennis and lose. I'm more interested in trying to win the match against Jo and playing the right tactics to give myself the best chance of doing that."
Murray claims his recent shortcomings against other top-10 players do not unduly prey on his mind.
"Not as much as you guys would think," he said. "I've beaten many top-10 players over the course of my career in these events, so I'm sure it will happen soon and I hope that's the case on Monday."
Murray has lost some of the aura he built up during those heady 12 months of Olympic, US Open and Wimbledon success. Tsonga hadn't beaten Murray for six-and-a-half years until a three-set victory over his friend in last month's quarter-finals in Toronto. Tsonga, and others, sense a vulnerability in Murray that had all but disappeared.
Tsonga illustrated as much by overturning a 3-0 deficit in the final set in Canada and it was revealing to hear him talk to a group of French writers in the run-up to this US Open fourth round match.
Tsonga spoke of the increased self-belief which stems from beating Murray, Djokovic, Dimitrov and Roger Federer on consecutive days in Toronto. But he also offered the observation that Murray is not "serving or hitting as strongly" since his return from back surgery.
He also pointed out that his serve is less reliable, before adding in a BBC interview in English: "You move differently because you want to keep your injury safe, and then it can make you do some bad choices on the court."
There is much to occupy Murray's mind right now. Other than proving to his peers that he deserves to retain his billing as a member of the 'big four', he needs to shore up a ranking which has slipped to number nine.
That is also the position he occupies in the ATP's Race to London. Murray will have to close a significant gap on Tomas Berdych if he is to move into one of the eight qualifying positions for November's World Tour Finals. Tsonga and Kei Nishikori are also breathing down his neck.
Murray's Davis Cup teammate Colin Fleming believes some of that tension is likely to have played a part in the severe cramping his fellow Scot suffered just an hour-and-a-half into his first-round match with Robin Haase.
|Murray v Tsonga Head to Head statistics|
|Andy Murray||2014 to date||Jo-Wilfred Tsonga|
|9||Current ATP World ranking||10|
|0||Titles||1 (ATP World Tour Masters 1000 Canada)|
|W: 0L: 5||Results against top-10 players||W: 4L: 7|
|Source:ATP World Tour website as of 31.08.2014|
"I saw his quotes before the tournament - talking about rediscovering his love of the game, and enjoying the challenge out there on the court," Fleming told BBC 5 live earlier in the championships.
"I've said these things to myself before matches and it doesn't matter how much you try and say it to yourself. In a tournament like the US Open, especially one that is so dear to Andy, there are undoubtedly going to be nerves."
The last time Murray failed to reach the quarter-final of a Grand Slam he entered was in New York four years ago. He has a phenomenally consistent record, and only Federer, Nadal, Djokovic and Andre Agassi have won more Grand Slam titles this century.
It may well be that 2014 turns out to be a fallow year - undermined by the repercussions of back surgery and the departure of Ivan Lendl - but Murray has an opportunity this week to show that while form can be temporary, class is permanent.