Top-ranked Novak Djokovic bowed out of the ATP World Tour Finals, suffering an upset from Janko Tipsarevic.

Djokovic won his first 43 games in 2011, en route to capturing three grand slam tournaments. However, his campaign will be cut short as the year ends.

Tipsarevic ousted Djokovic 3-6, 6-3, 6-3 in Group A action. This was the Serbian’s second defeat—the first came from David Ferrer.

Tomas Berdych earned a semifinal berth with a win over Ferrer, who has already clinched a spot in the final four. Ferrer will face off against Roger Federer, while Berdych will be matched against Jo-Wilfried Tsonga.  

Federer breezed through Group B action, while his rival—Rafael Nadal—failed to reach the semis.