The Argentine saved three-match points in a rip-roaring deciding set with Roger Federer before securing a monumental 6-4 6-7(8) 7-6(2) victory.
A second tier title was the one noticeable omission on del Potro’s list of achievements, but he’s now accomplished another of his goals – at the 52nd attempt – after a bad-tempered tussle with the shell-shocked Swiss.
It’s a 22nd career title for the Argentine, and he has extended his winning running to 11 matches.
Del Potro had the opportunity to seal the win earlier than he did; however he squandered a match-point opportunity in the second set and became embroiled in a shootout for the trophy.
Federer, who was agitated and irritable throughout the intense battle, let three match-points slip by in the decider as he served for an unprecedented sixth title. It was a painful defeat for the world No.1, and his unbeaten start to the season is over.
It was the type of heavyweight contest that tennis watchers have become accustomed to over the last decade, yet rarely witnessed in 2018.
It was a fascinating duel that will long be remembered, and del Potro is once again a contender for the biggest prizes after a spell in the wilderness.
Federer struggled with his backhand during his last four scrap with Borna Coric on Saturday – and his forehand misfired in the early stages of the final.
Del Potro was rarely troubled on serve and he moved a break in front when Federer dumped a forehand in the net. Del Potro had a 3-2 lead, and that was all he required to take the opening gambit.
The second set was closely fought, and both competitors were clinical behind their respective deliveries. Federer did create two chances to break in the 10th game, however his opponent refused to buckle.
A tiebreak was necessary and it was a must-win for the world No.1. Del Potro snared a rare mini-break and established a match-point opportunity, however he netted a mid-court forehand that he would normally gobble up.
It was a let-off for Federer, and he made the most of his reprieve. He eventually edged a nerve-shredding shootout after del Potro nudged a volley beyond the baseline.
It had been a tiebreak filled with tension, and neither competitor was particularly enamoured with the work of umpire, Fergus Murphy. Del Potro repeatedly stated his annoyance with the spectators calling out between serves, and his moaning frustrated Federer.
The on-court animosity only added to the drama though, and both players channelled their displeasure in the right manner.
The first major incident of the third set came in the 9th game. Federer nabbed a 5-4 lead after he flicked a backhand return cross-court – and suddenly he was within touching distance of a 98th title.
The Swiss created two match-point opportunities on his serve as he closed in on victory, but he failed to seal the deal. Del Potro cracked a forehand winner to save the first before Federer floated an ambitious dropshot into the net.
The Argentine saved a third match-point and then began a stirring and unlikely comeback. The 29-year-old pummelled a forehand winner to pull level and rekindle his trophy hopes.
The crowd were stunned by the unexpected turn of events, and Federer never quite recovered from the disappointment. The Swiss was barely competitive in the tiebreak, and the defence of his title ended in heartbreak.
This was del Potro’s moment in the sun though, and it won’t be the last time he upsets the odds this year.