Mesut Ozil has said he is still "very happy" at Arsenal but "something is not working with the team" at the moment.
Ozil's future is undecided as contract talks with Arsenal have been put off until the summer. Speculation has increased in recent weeks that Ozil and Alexis Sanchez, who is also yet to commit his future to the club, could be sold when the season ends, but Ozil told German news agency dpa that nothing has been decided.
"The fact is I've still got a contract in London," Ozil said in quotes reported by the Mirror. "To speculate now would be wrong. At the end of the season we will see, there will be talks. I'm very happy at Arsenal and in London."
Arsenal manager Arsene Wenger said this week that the club has put the contract talks with the star duo on hold after failing to come to an agreement with either. Wenger's own future is also in doubt as his contract expires this summer, with the pressure growing on the manager after a string of recent losses.
Arsenal are only sixth in the Premier League after losing four of their last five matches, and were knocked out of the Champions League 10-2 on aggregate by Bayern Munich.
"We are having a difficult phase. Somehow something is not working with the team," Ozil said. "We are letting in a lot of goals. Maybe it's down to self-belief. When I look at the quality of Arsenal though I'm convinced we will get on a run again soon."
Ozil has not started a game since the first 5-1 loss to Bayern in Germany because of illness and injury, and missed the national team's friendly against England on Wednesday with a hamstring problem.
Ozil has previously said he will not decide whether to stay at Arsenal until he knows what Wenger is doing. But he said the players are still in the dark regarding the manager's plans.
"I don't know what he will decide," he said. "That's something we will have to wait for."
Meanwhile, Robert Pires has told Sky Sports that Wenger signing a new deal at Arsenal is more important than extending the contracts of Sanchez and Ozil.
"I hope for him [Sanchez] and Ozil they extend with new contracts. The negotiation is very difficult and maybe complicated," Pires said.
"But the most important is to see Arsene Wenger extend. Arsene Wenger is very, very important for Arsenal for now and for next season. I believe in Arsene Wenger. For me it was a privilege to work with him for six seasons. He was not perfect but he was good, we won some titles."
Information from the Press Association was used in this report.