It was Del Potro’s 11th consecutive match win and second title in a row, having won the Acapulco title two weeks ago.
The sixth-seeded Del Potro was competing in his first Masters 1000 final since 2013 and his third title match of the season.
“Well, I’m still shaking. I think this is the worst part for me. First of all I want to congratulate Roger on a great week, great success in this start of the year, you’re making history and I’m so happy to be just behind you seeing what you do, it’s amazing for our sport and for the life,” said Del Potro in the trophy ceremony.
“I cannot believe I’m here with this trophy, beating Roger after a great battle. I was really angry after the second set, but well I was lucky in the last tiebreak I played well and finally I got the trophy.
“Thank you to my team, thank you for supporting me, to stay with me in the good moments and the bad moments. You’re very special, I share this trophy with you.”
Addressing the crowd he added: “Thank you very much for the respect in this final, you were an unbelievable atmosphere. Thanks for giving me so much love to never give up after all my injuries.”
He took his tally to 22 career trophies and became just the second man outside of Federer, Rafael Nadal and Novak Djokovic to win Indian Wells in the past 15 years.
The 29-year-old denied Federer a sixth trophy in the California desert and 98th career title.
Prior to this fortnight, Federer, Novak Djokovic and Rafael Nadal had won 13 of the past 14 Indian Wells title, dating back to 2004, with the only exception being Federer’s coach, Ivan Ljubicic, triumphing in 2010.
Del Potro entered the contest trailing Federer 6-18 in career meetings but with a 3-2 advantage over the Swiss in finals.
Federer saved a match point in the second set and served for the title in the decider but Del Potro pegged him back to triumph in the end.
The Argentine drew first blood, breaking at love for a 3-2 lead and he secured the opening set in 34 minutes by holding at love.
Federer, contesting his eighth Indian Wells final, faced two break points at the start of the second set but he saved both to hold for 1-0.
They stayed neck and neck until they went to a tiebreak, with Del Potro needing to save two set points in game 10.
An inside-out forehand winner gave Federer a minibreak for 4-3 and he got his hands on three set points moments later. Del Potro saved the first two, on his own serve. Federer thought he took the set with a service winner on his third chance and started celebrating but Del Potro challenged and the serve was out. Federer then double-faulted and they were back on serve at 6-6 in the breaker.
Federer was getting more and more flustered and argued with the umpire during the change of ends then aced to get a fourth set point. Del Potro saved that too, with a good serve.
Another good serve and Del Potro got himself a match point. The Argentine netted a forehand and it was 8-8. A long forehand from the No. 6 seed gave Federer a fifth set point. This time, some incredible defence from Federer followed by a long volley from Del Potro sealed the set for the Swiss to force a decider.
A leaping backhand smash gave Federer a break point in the ninth game of the third set. But a strong serve-forehand combo helped Del Potro out of trouble. Still Federer found a way to break and put himself in the position to serve for the title.
The Swiss aced to get two match points but Del Potro saved both and created a break point opportunity. Federer hit Del Potro with a shot up at the net to save it.
— doublefault28 (@doublefault28) March 18, 2018
The world No. 1 then got a third match point but his drop shot was chased down by a sprinting Del Potro who found the passing shot he needed to save it.
A Federer shank gave Del Potro another opportunity to break and this time the big-hitting Argentine slammed a crosscourt forehand winner to draw level at 5-5.
Both players held serve and the title showdown all came down to a final-set tiebreak.
Del Potro raced to a 5-0 lead in the breaker and got match points at 6-1. The first one slipped away on a long error from the No. 6 seed but he converted on the next point to wrap up a memorable victory.
“I’m really happy to be here, except the losing part, that’s tough, but I’m so happy to be back in the finals here at Indian Wells. Had a great week on and off the court,” said Federer after his loss.
“Most importantly, Juan Martin, well played today. There wasn’t much between us but you deserve it, well done.”
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