The 22-year-old attacking midfielder must wear a cast for the next 14 days and is expected to miss the next six to eight weeks after limping off in Saturday's 3-3 draw at home to Hoffenheim.

He is definitely out of Tuesday's Champions League quarter-final, first leg at Manchester United, as well as the return leg in Munich on April 9 and the semi-finals at the end of April should Bayern progress.

"That is bad news, we will miss him very much," said Bayern coach Pep Guardiola.

With the Bundesliga title now secured with a record seven games to spare, the timing of the injury is a blow with Bayern's bid to become the first team to defend the Champions League title.

"That's extremely bitter news and comes at a catastrophic time for us, just before the important matches," said Bayern's Germany winger Thomas Mueller.

Thiago is expected to be fit for Spain at the Brazil in World Cup, which kicks off on June 12, and has been a key component in Bayern's midfield with the pinpoint accuracy of his passing.

This is the second significant injury Thiago, who joined Bayern from Barcelona in July, has suffered this season after spending two months onthe sidelines with an ankle injury he picked up last August.