It has become the riddle of the summer. How on earth did Juan Mata slide from being Chelsea's player of the year to the fringe of the team?
Supporters are certainly baffled, as are rival managers who made enquiries about signing the 25-year-old after he was left out of the team at Manchester United on Monday.
Tottenham were quick to let it be known they were interested and Arsene Wenger went as far as to admit Mata 'could be on the market'.
Playmaker: Juan Mata (right) looks set for a bit-part role at Chelsea after his heroics in the past two years
Watching: Jose Mourinho says he wants to keep Mata, but the Spaniard has barely featured this season
Three amigos: But Mata hasn't taken up his usual space alongside Oscar (left) and Eden Hazard
Chelsea and Jose Mourinho deny they want to sell and Mata does not want to leave but he is intelligent and mature enough to work it out for himself.
He is not someone prone to tantrums or to demand showdown talks and accepts that he missed early pre-season and Chelsea's tour of Asia after international duty at the Confederations Cup.
He also realises there has been managerial change and he will need time to understand what Mourinho expects of him.
Barring an unforeseen chain of events, Mata will not leave Stamford Bridge before Monday's deadline but he will reassess his position in January.
Mourinho wants to play high-tempo and intense football and this includes a tireless work ethic from the four most advanced players in his 4-2-3-1 formation.
The glory: Mata has been Chelsea's shining light in his two years at the club
Silverware: Mata (left) lifting the Europa League trophy with team-mates last season
Jump for joy: Mata has been Chelsea's Player of the Year for the past two seasons since his arrival
It is the reason behind his pursuit of Wayne Rooney and his decision to move for Samuel Eto'o, who performed such a role for him at Inter.
Willian, who completed his move to Chelsea on Wednesday after acquiring a work permit, may not be combative like Rooney but he is quick and willing to close down spaces.
Mata, it must be said, does not do this. In fact, he rarely contributes off the ball.
After hijacking Willian's transfer to Tottenham last week, Mourinho rejected the idea he wanted Mata out and stressed he would need many quality players for these positions to achieve what he was after.
New signings: Mata will have to compete for playing time with Andre Schurrle and Willian (below)
This week, however, Chelsea were in talks for yet another winger: Christian Atsu, a 21-year-old Ghanaian international from Porto.
Mata appears to be staring at the prospect of being the new Joe Cole, gifted footballer and darling of the fans but under-appreciated by Mourinho and certainly not central to his plans.
One significant difference is that Roman Abramovich adores Mata as one of the few recruitment successes of the post-Mourinho era and one of the creative forces who brought attractive football to Stamford Bridge.
Wenger, having been so close to signing Mata when he left Valencia in 2011, will monitor the situation closely and has asked to be kept update on any developments.
First time around: Mourinho tried to teach Joe Cole to play more for beneficially for the team
Mata's father (also his agent) was spotted at the Emirates as Arsenal beat Fenerbahce in the Champions League on Tuesday.
Villas-Boas, the Chelsea manager responsible for identifying Mata, is also keen but on Wednesday rejected the idea that Mourinho would sell an influential player to a fierce rival like Tottenham.
'Mata is a great, great player and very, very important for Chelsea,' said the Spurs boss. 'They are not just going to strengthen another team who they think are rivals for the title.'
Work ethic: Mourinho will want Mata, challenging Christian Benteke, to add a defensive element to his game
The idea that Mata may be available to teams outside England is supported by reports in Spain this week that he was offered to Atletico Madrid.
One outcome which may appeal to Mourinho (if not Chelsea fans) would be to swap Mata for Rooney, but Chelsea appear to have accepted defeat on Rooney.
And so it remains a riddle.