Juan Martin Del Potro of Argentina caused one of the biggest upsets of the ongoing US Open, defeating 19-time Grand Slam champion Roger Federer in the quarterfinals of the men's singles event on 6 September.
Del Potro came out with a vintage display of power tennis and defeated Federer 7-5, 3-6, 7-6, 6-4, to advance to the semifinals at the Flushing Meadows for the first time since winning the title in 2009, when he defeated the Swiss maestro in a classic five-set final.
The result of the semi-finals denied Federer a shot at Nadal in the semi-finals in a match that would have given him the chance to dethrone the Spaniard as World No. 1. Federer and Nadal have never played at Flushing Meadows.
Del Potro's shock victory over the number three seeded is even more remarkable considering his journey to the quarterfinals.
The big-serving Argentine had earlier defeated Dominic Theim, winning the most memorable match of the tournament so far this year.
In the fourth round clash against Thiem, Del Potro initially struggled and lost the first two sets with illness. But he stormed back to claim one of the most memorable comebacks in U.S. Open history and setting up a much-anticipated clash with the Swiss legend.
Del Potro, world No. 28, will face top-ranked Rafael Nadal in the semifinal on Friday.
For the five-time US Open champion, it was the fourth loss of what has been a highly successful Grand Slam season that saw him win both the Australian Open and Wimbledon.