Thiago was forced off midway through the first half of the 2-0 friendly victory in Alicante and a scan on Saturday showed swelling on the medial collateral ligament, Spain said on their website (www.sefutbol.com).
The 24-year-old playmaker's career has been disrupted by a series of knee and ankle problems and he missed last year's World Cup finals in Brazil after needing surgery to repair ligament damage in his right knee.
"Given the player's surgical history and to maximise preventative measures he has left the squad to be treated by Bayern Munich medical staff," Spain said.
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Bayern's next match is a Bundesliga clash at Schalke 04 on Nov. 21.
(Reporting by Iain Rogers, editing by Ed Osmond)
