Manchester City manager Roberto Mancini has told Samir Nasri he must improve ahead of Sunday's showdown with his former club Arsenal.
Nasri has failed to command a regular spot in Mancini's impressive side since his high-profile £24million move from the Gunners in August.
The France international showed glimpses of his talent as he made four successive starts recently but he was back on the bench as the Premier League leaders lost at Chelsea on Monday.
The 24-year-old faces stiff competition for a place in star-studded City's midfield but Mancini has no doubts about his ability.
Mancini said: "In my opinion Nasri is a champion - a top, top player. I think he can do more but when you change teams you can have a problem.
"At this moment his confidence is maybe not very good because he didn't play against Chelsea but if he plays Sunday he has a chance to show us.
"I would like Nasri to play better, because he is a really good player."
Mancini similarly demanded improvement from winger Adam Johnson earlier this season despite some impressive performances from the former Middlesbrough man.
Mancini believes players of their talent should be delivering to high standards consistently, yet he accepts he cannot always accommodate them.
He said: "When you play with two strikers and Samir and (David) Silva, you have more chances because you attack.
"But there will be some moments when it is difficult to support all the offensive players all the time.
"I need to change sometimes but Samir is a good player."
Nasri's recent run in the side included the Carling Cup quarter-final victory at Arsenal, during which he was barracked throughout by home supporters.
He responded with a superb performance in the 5-1 thrashing of Norwich and Mancini now wants him to step up again, especially with midfield linchpin Yaya Toure heading to the African Nations Cup in January.
Mancini said: "I think we will lose an important player but I hope Samir can play more games at a higher level.
"He is a top player. Every game a player like that should contribute."
What will the result be between Man City and Arsenal?
Man City win