Robert Lewandowski Bayern Munich
Robert Lewandowski has a contract with Bayern Munich until the summer of 2019Reuters

Bayern Munich star forward Thomas Muller has claimed that lethal striker Robert Lewandowski has a contract to fulfil at the Allianz Arena and only time can say whether the Poland international prefers to move to one of his suitors in the coming transfer windows.

Lewandowski, who has made his name as one of the best goalscorers in European football, has attracted a lot of attention from European powerhouses Real Madrid, PSG, Manchester United and Liverpool over the previous transfer windows.

The striker, who has a contract with Bayern until the summer of 2019, is a hot prospect in Europe, with these top sides chasing his prized signature.

"I do not know how serious the interest [from the clubs] in him [Lewandowski] really is," Muller told German newspaper AZ. "The transfer market is not open right now. Plus he still has plenty of time left on his current contract. But it is clear that he is a very important player for Bayern."

Real Madrid are reportedly ready to shell out £75m to get their hands on the player, who has scored 31 times so far this season for the Bavarians from 32 games.

Lewandowski also recently said that he is keen on another long-term contract with Bayern Munich as he feels the chemistry, balance and the shape of the team is just perfect. "I know that there is interest from abroad [for me]," Lewandowski had told Sportbild. "But I can very well imaging putting pen to paper on a new deal here because of the super team and the good cooperation, because the club is known to honor good performances."

Muller, meanwhile, also spoke about the need of fulfiling a certain contract with a club before moving to another. The Germany international, another transfer target for Manchester United, signed a contract extension with Bayern Munich until 2021, last December. 

"When you sign a contract, you expect to actually fulfill it," the 26-year-old said. "There is still a long time to go, but the club and I are both happy with each other. And I am already over 30 when my contract expires.

"I hope to be able to keep playing at a level high enough to remain successful at Bayern."