The Dutchman, who has broken the big toe on his right foot, will undergo surgery on Monday.

"It's a real blow for me personally, especially as it's all started so well," the 32-year-old said on the club's official website.

"I'll be back as soon as I can, and I'll pick it all up where I've left off."

Van Bommel's injury is the latest setback for Bayern, whose start to the season has been overshadowed by injuries to key players.

Coach Louis van Gaal was already deprived of the quartet of Franck Ribery, Martin Demichelis, Miroslav Klose and Luca Toni for yesterday's Bundesliga opener and was forced to give young defender Holger Badstuber his debut.

Nevertheless, the Dutch coach was satisfied with the outcome, despite some early teething problems.

"The team forgot to play football in the first half," he said. "We did not adjust to the situation and that was unprofessional.

"We were good in the second half, though. After the game, I had the feeling that we even should have won.

"We had chances but did not take them."

Van Gaal will hope to have Ribery back for his side's second game of the season at home to Werder Bremen next Saturday.

Summer signing Anatoliy Tymoshchuk could make his full Bundesliga debut in place of van Bommel.