before entering a third set tiebreaker.
At 4 all, del Potro netted a forehand then struck another crosscourt forehand long to face set point.
However after several groundstroke errors from Federer, del Potro would save four set points before leveling the tie breaker at 8 all with an inside out forehand down the line winner.
Del Potro struck a down the line forehand volley winner to lead 9-8 before Federer struck a down the line backhand volley long to lose the set.
With Federer serving down breakpoint at 2 all in the final set, del Potro stuck a crosscourt backhand passing shot winner to break serve and lead 3-2.
Four service game holds later, del Potro served for the match at 5-4.
The Argentine struck a 128 miles per hour ace out wide to lead 30-0.
Then at 30 all, Federer sent a crosscourt forehand volley long to face match point.
A 130 miles per hour serve out wide from del Potro set up a Federer crosscourt backhand stab return which del Potro hit for a down the line forehand winner to end the match.