10 most painful Grand Slam defeats for Roger Federer

#4 2011 US Open semi final: Djokovic beats Federer 6-7(7) 4-6 6-3 6-2 7-5

Djokovic was Federer's nemesis for the second straight US Open semifinal

Facing the prospect of a first season in nine years without a Grand Slam title, Federer faced Djokovic in a fourth consecutive US Open semi final. Determined to avoid another semi final ouster against the same opponent at the last major of the year, Federer took a two-set lead only for Djokovic to storm back into contention by taking the following two sets to force a fifth.

The Swiss dialled in on serve, broke the Serbian in the ninth game, and served for the match. At 5-3 40-15 Federer failed to convert two match points on serve, as Djokovic won the final four games of the match to inflict a second consecutive US Open semifinal misery on the Swiss, and thwart the possibility of a first Federer-Nadal final at Flushing Meadows for a second straight year.