The Spanish midfielder sustained the injury in Saturday's 2-0 victory over Nuremberg.
The 22-year-old had a scan on the ankle after the game, which showed the extent of the damage.
It is understood that the former Barcelona man will have an operation on the injury tomorrow.
Thiago joined Bayern this summer from Barcelona, reuniting with boss Pep Guardiola.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Bayern MunichBayern | 9 | 7 | 2 | 0 | 32 | 7 | 25 | 23 |
| 2 | RB Leipzig | 9 | 6 | 2 | 1 | 15 | 5 | 10 | 20 |
| 3 | Eintracht FrankfurtFrankfurt | 9 | 5 | 2 | 2 | 23 | 14 | 9 | 17 |
| 4 | Bayer LeverkusenB. Leverkusen | 9 | 4 | 4 | 1 | 20 | 15 | 5 | 16 |
| 5 | Borussia DortmundDortmund | 9 | 5 | 1 | 3 | 17 | 15 | 2 | 16 |
| 6 | Freiburg | 9 | 5 | 1 | 3 | 13 | 11 | 2 | 16 |
| 7 | Union BerlinUnion Berlin | 9 | 4 | 3 | 2 | 9 | 8 | 1 | 15 |
| 8 | Stuttgart | 9 | 3 | 4 | 2 | 17 | 16 | 1 | 13 |
| 9 | Borussia MonchengladbachBorussia M'bach | 9 | 4 | 1 | 4 | 15 | 14 | 1 | 13 |
| 10 | Werder Bremen | 9 | 3 | 3 | 3 | 15 | 20 | -5 | 12 |
| 11 | Augsburg | 9 | 3 | 2 | 4 | 13 | 20 | -7 | 11 |
| 12 | Heidenheim | 9 | 3 | 1 | 5 | 12 | 12 | 0 | 10 |
| 13 | Mainz 05Mainz | 9 | 2 | 4 | 3 | 12 | 13 | -1 | 10 |
| 14 | Wolfsburg | 9 | 2 | 3 | 4 | 16 | 17 | -1 | 9 |
| 15 | St Pauli | 9 | 2 | 2 | 5 | 7 | 11 | -4 | 8 |
| 16 | Hoffenheim | 9 | 2 | 2 | 5 | 13 | 19 | -6 | 8 |
| 17 | Holstein Kiel | 9 | 1 | 2 | 6 | 11 | 23 | -12 | 5 |
| 18 | VfL BochumVfL Bochum | 9 | 0 | 1 | 8 | 9 | 29 | -20 | 1 |
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