The Frenchman sustained a setback in training earlier this week and he has subsequently missed the last two games for the London giants.
Speaking after the 3-1 Premier League win over Liverpool, Maresca provided an update on him saying: "He will be out for one week or two weeks, 10 days."
Nkunku has had a frustrating second season with the Blues and he has played second fiddle to Nicolas Jackson for the centre-forward role.
He is poised to leave the club at the end of the campaign and reports have claimed that Arsenal and Bayern Munich are keen on his services.
Maresca has said that he won't be available for a couple of weeks but we won't be surprised if the absence is expected for the rest of the season.
Nkunku has made the decision to move on from the Blues.