Del Potro played some extremely aggressive tennis early on and as he result he claimed the 1st set 6-2.
Federer dug deep however and tried to keep himself in the contest, a straight sets defeat would have seen the World Number 1 eliminated from the tournament and this seemed like when Del Potro was 5-4 up in the tiebreaker but Federer turned it around to level the match.
Del Potro was not to be denied though, he broke Federer in the 8th game of the decider and then held his serve to claim a superb 6-2 6-7 6-3 victory.
The result sees the British Number 1 Andy Murray eliminated from the competition, Murray won two out of his three matches but was beaten in 3 sets by Federer on Tuesday.
If Del Potro can maintain this form then it would take a brave person to Bet against him winning the title on Sunday.