Roberto Mancini has admitted Manchester City have not seen the best of Patrick Vieira.
The former Arsenal skipper arrived at Eastlands in January with high expectations after quitting Inter Milan's Champions League quest.
Yet Vieira was not able to play until the beginning of February due to a calf injury suffered in his final game for Inter and then had to serve a three-match suspension following an incident with Glenn Whelan during a Premier League game at Stoke that escaped the attention of referee Alan Wiley at the time.
Since then, the Frenchman has struggled for form, and was below-par in Monday night's victory over Wigan, which kept City in line for a top-four finish.
Mancini still has plenty of faith in the 33-year-old, but accepts the need for further improvement.
"Patrick is probably not playing like the player everyone knows," said Mancini.
"When he arrived here he had an injury, although after that he improved before he had to miss another three games.
"He could improve but he needs to play more games because Patrick can be an important to us."