Juan Martin del Potro battled back from two sets down and saved two match points to beat Dominic Thiem 1-6 2-6 6-1 7-6 (7-1) 6-4 in the US Open fourth round on Monday.

The Argentine, a previous winner at Flushing Meadows in 2009, struggled with illness but he showed great mental strength to battle through in three hours and 35 minutes.

The 28-year-old, who has suffered from numerous injury problems since claiming his maiden Grand Slam title eight years ago, admitted after the match that it was one of the most “epic contests” he has ever played in.

“I played one of the epic matches of my career here at the US Open, which is my favourite tournament, in front of a great crowd,” Del Potro said.

The former world number four also conceded that he considered retiring midway through the second set, as he did not feel physically up to the battle against sixth seed Thiem.

He added: “I couldn’t breathe, I couldn’t move well, and Dominic was dominating the match so easy.”

Del Potro’s reward for reaching the last eight is a clash with five-time champion Roger Federer, who secured a straight-sets victory over Philipp Kohlschreiber in his own fourth-round match.

The quarter-final showdown will also be a repeat of the 2009 final in New York, a match Del Potro won in five sets.