Arsenal boss Unai Emery said Aaron Ramsey must only focus on training and playing football amid uncertainty over his future.
Ramsey is out of contract at the end of the season and the Wales star is yet to agree to a new deal at Arsenal, having been linked with Chelsea and Barcelona.
However, Ramsey was left out of the starting XI in last week's 3-2 Premier League loss to Chelsea, coming off the bench for a 22 minute spell.
And Emery has called on Ramsey to forget about contract talks, saying it is something for the club and his representatives to work out.
"I spoke with him last week," Emery said. "I said: 'I want you focused only on training and only on the match, you show us the capacity to help the team'.
"The contract is another thing for his agent and the club but we want and I need his focus only on training, only on the match and on his performance each day."
Having started on the bench at Stamford Bridge, Ramsey could return to the line-up for Saturday's clash against London rivals West Ham, who are also winless after two games.
Emery conceded the approach to facing West Ham will differ from the last two Premier League champions, with a greater belief the team can dictate the proceedings.
"Manchester City are a different team and so the preparation is very different compared to other matches," Emery said. "Also, Chelsea are different to other teams. We have to work specifically to prepare for them.
"Saturday is also a difficult match, but we are thinking more we can control the match, with our personality. Against Chelsea and Manchester City we wanted to control with our personality, but there were more times in the 90 minutes that the opposition did not let us do that."