Chelsea manager Jose Mourinho has declared Juan Mata will continue to be a fringe first-team player until he adapts to the club's new style.
Mata, who was Chelsea's player of the year for the last two seasons, has struggled to break into the starting XI since Mourinho has taken over at Stamford Bridge.
The sporadic use of the Spaniard has perplexed Blues fans but Mourinho has made no apologies for his decision and says Mata has work to do if he is to become a regular starter.
Mourinho hinted Mata, who wants to play in the 'number 10' role, had to be prepared to play in a wider role and says Oscar is the first-choice for that position behind the lead striker at the moment.
"The way I'm reading the situation and the reasons why, in this moment, he's (Mata) not playing so much are things I can speak about with him but not publicly," Mourinho said on Friday.
"But he played against Everton from the start and you can analyse his performance. He came on against Basel when the team were winning 1-0 – not like Demba Ba or Mikel John Obi, who came on to rescue the game –with specific tasks to do.
"It's part of a process with him, too. It is one thing to play with Ramires and Oscar closing down opponents on each side, and Mata as a number 10, behind a striker with his clever assists, clever passes and fantastic actions because he has great talent.
"But it is another thing to adapt to the way we want to play. In this moment, Oscar is my number 10 and, if anyone tells me Oscar has not been Chelsea's best player this season, I'd have to disagree.
"I have to prove to the fans that I am good. Now (Mata) must do the same."
Mata, who has been a key member of the Chelsea side that has won the UEFA Champions League and UEFA Europa League over the last two seasons, has featured in just three matches under Mourinho.
Along with Oscar and Eden Hazard, Mata was regularly part of an exciting attacking triumvirate behind a lone striker last season, and Mourinho says there is no reason that cannot be successful again.
"But only when (Mata) adapts to what we want," Mourinho said.
"I'm not ready to ask Oscar to track opposing full-backs. Brazil has more talented players in the number 10 position than any other country in the world, and he plays there for the national team, so I want to build with Oscar as my number 10.
"I want the other two players, from the side, to adapt to that reality and learn how to do things they were not ready to do before.
"The players are open to some of the changes.
"If I'm an attacking player I'd prefer to play without a position, without certain responsibilities, and with others behind me to cover so I don't need to worry about (tracking back). It's about changing mentality.
"It takes a bit of time. But it won't take five, six, seven years. I promise."
Mourinho also said the Blues slow start to the season, which includes back-to-back losses in the Premier League and the Champions League, is due to a change in the team's playing style he is trying to implement.
"I don't like the way Chelsea were playing the last couple of years; the club doesn't like it and we want to change," the Portuguese said.
"We want to play a different style. The past is history – even my past. I'm here like I've just arrived."
|Rakitic hails ´patient´ Barcelona after Real Betis rout|
|Neymar? I´d rather watch the golf, says Bale|
|Mbappe injury from goalkeeper collision ´nothing serious´|
|Don´t look back - Guardiola gives Manchester City title warning|
|Vermaelen to face tests on new hamstring injury|
|Conte wants ´point of reference´ striker as Barnes joins surprising Chelsea links|
|Sane the perfect tonic to Sanchez blues for City and Guardiola|
|Suarez scores 100th LaLiga goal as Messi reaches new milestones|
|Lyon 2 Paris Saint-Germain 1: 10-man leaders downed by twin wondergoals|
|Inter 1 Roma 1: Vecino snatches point on possible Dzeko farewell|
|Real Betis 0 Barcelona 5: Messi, Suarez rampant as leaders go 11 points clear|
|PSG star Mbappe injured in goalkeeper collision|
|Monchi: Roma will replace Dzeko|
|Kessie a far better player than I was, claims AC Milan coach Gattuso|
|Neymar to Real Madrid stories manufactured by Spanish press, claims Marquinhos|
|Cagliari 1 AC Milan 2: Kessie at the double in comeback win|
|Watford hire Javi Gracia as Marco Silva successor|
|I am happy with our squad - Pochettino denies Malcom rumours|
|Not much changed - Zidane boosted by clinical Madrid|
|No chance of January move, says Vidal|
|Selfie or stitches? Ronaldo bloodied after Madrid brace|
|Heynckes hails Bayern win: This is what sets us apart|
|Southampton 1 Tottenham 1: Kane earns visitors a point|
|Silva assured of chances at AC Milan after latest first-team snub|
|Goretzka´s Schalke return marred by abuse|
|Real Madrid 7 Deportivo La Coruna 1: Seven-up for Zidane´s men as Bale shines|
|Muller brings up 100 Bundesliga goals in Bayern win|
|Bayern Munich 4 Werder Bremen 2: Lewandowski & Muller at the double to spare champions´ blushes|
|Do Arsenal or Man Utd get the better deal? Sanchez v Mkhitaryan in Opta numbers|
|Pele ´fine´ and in ´no pain´ after reported health concerns|
|No mercenary? Sanchez endorses article defending imminent Man Utd move|
|Allegri expects Buffon to be ´fully recovered´ within a week|
|Atletico Madrid confirm Costa hamstring injury|
|Atalanta 0 Napoli 1: Mertens ends drought to keep visitors top|
|Alexis Sanchez boards plane ahead of reported Man United medical|
|Hamburg dismiss Gisdol after fourth loss in a row|
|Melbourne City 5 Adelaide United 0: Budzinksi & Vidosic braces inspire emphatic win|
|Marco Silva sacked by Watford following ´significant deterioration´|
|Deschamps knows my thoughts - Lucas Hernandez hints at France decision|
|Klopp: Liverpool wouldn´t sell to rivals during season|
|Giggs keen to help Bale overcome injury woes|
|Klopp in no rush to replace Coutinho|
|Malcom dreams of Premier League but remains unsure of future|
|Guardiola sets target of 10 wins to guarantee title|
|Championship Review: Millwall break Leeds hearts in seven-goal stunner as Wolves lose|
|Messi and Pique welcome Coutinho to Barcelona training for first time|
|Thauvin ´very happy´ at Marseille|
|Guardiola salutes ´outstanding´ Manchester City|
|Watford still battling relegation from the top half, insists Silva|
|Rondon ´devastated´ after Everton´s McCarthy suffers horror injury|
|Aguero´s perfect hat-trick is Argentine´s 11th for Manchester City|
|Moyes impressed with Hammers display despite being held by Bournemouth|
|Dyche annoyed with Burnley´s ´big six´ results|
|Manchester City 3 Newcastle United 1: Aguero hat-trick sees pacesetters bounce back|
|Everton fans´ frustration understandable, says Allardyce|
|Wenger responds to Dortmund criticism over Aubameyang affair|
|Bordeaux appoint Poyet as new boss|
|Mourinho frustrated at United failure to ´kill´ Burnley|
|Simeone reveals Costa knock as Atletico bemoan dropped points|
|Lambert upbeat over Stoke´s quality after debut victory|
|Nothing happening with Aubameyang - Wenger|
|Mourinho, Wenger expect imminent Sanchez deal|
|Everton confirm McCarthy double leg break|
|Valverde talks of ´respect´ for Atletico as Griezmann saga turns again|
|Rafinha misses Barca training with Inter closing in|
|Neymar misses Lyon clash with thigh injury|
|Atletico Madrid 1 Girona 1: Griezmann substitution costs Simeone|
|Everton 1 West Brom 1: McCarthy horror injury overshadows cagey draw|
|Leicester City 2 Watford 0: Vardy & Mahrez decisive as Puel´s men go seventh|
|West Ham 1 Bournemouth 1: Hernandez proves his worth to Hammers|
|Burnley 0 Manchester United 1: Martial keeps up winning run|
|Arsenal 4 Crystal Palace 1: Early blitz means Sanchez is hardly missed|
|Stoke City 2 Huddersfield Town 0: Lambert makes winning start as Potters inch out of bottom three|
|Crisis, what crisis? Conte lambasts Chelsea critics|
|A goal, two assists and an injury - Monreal the Sanchez replacement at Arsenal?|
|Monchi has no interest in weakening Roma squad amid Dzeko reports|
|Hazard delights in Willian and Batshuayi link-up|
|No January exit for AC Milan´s Silva, assures Gattuso|
|Spalletti: Roma game will not decide Inter´s fate|
|Brighton and Hove Albion 0 Chelsea 4: Hazard dazzles as Conte´s men get back on track|
|Dortmund confirm Arsenal bid for Aubameyang|
|United target Sanchez remains absent for Arsenal vs Palace|
|Zidane quiet on ´great´ Neymar with BBC ready to return|
|Hazard scores 100th league goal as Chelsea find shooting boots|
|Zidane: I will never throw in the towel at Real Madrid|
|Willian marks 50th consecutive Premier League outing with a goal|
|Noble shares West Ham bonuses with club staff|
|Barcelona refute claims of Griezmann agreement|
|Courtois out for Chelsea as Caballero steps in to face Brighton|
|Real Madrid´s Vallejo suffers hamstring injury|
|A-League Review: Bobo hauls in Mariners as Jets are grounded|
|Captain Jack? Wenger talks up Wilshere leadership qualities|
|I prefer Fekir to Neymar - Lyon president Aulas fires another pre-match barb at PSG|
|Dortmund boss Stoger leaves door open for Aubameyang return amid Arsenal links|
|Neymar can play with Ronaldo at Real Madrid – Mijatovic|
|Dyche compares Sanchez-Man United move to Harry Potter|
|Schurrle annoyed at more dropped Dortmund points|
|Carrick expected to become Man Utd coach, reveals Mourinho|