Mesut Ozil should leave Arsenal for Bayern Munich if he wants to improve his chances of winning a major title, says Michael Ballack.
The Arsenal playmaker has yet to put pen to paper on a deal at the Emirates, with the 28-year-old's contract set to expire in June of 2018.
A number of Europe's biggest clubs have expressed interest in signing the former Real Madrid and Schalke star, and Ballack says his best bet would be a return to the Bundesliga.
"Mesut is an amazing player. He knows that he is one of the undisputed stars at Arsenal," Ballack told Sport Bild.
"A lot of clubs would love to have him.
"But if he wants to win a major title, he has a bigger chance to achieve that at Bayern."
Should he exit the club, Arsenal would not allow Ozil to leave for a bargain fee. However, Ballack doesn't think a high price tag would be a problem for Bayern.
"If you look at the recent developments in England and China, it seems inevitable that Bayern will soon pay transfer fees of €50 million or so as well," Ballack said.
"They have to if you want to keep competing with the best.
"If you want to bring in world-class player, you will have to invest."