We can't get enough of lovable spoiler Juan Martin del Potro

NEW YORK -- The match was over, its storybook ending ripped from the semifinal pages of its book. There would be no Federer-Nadal on Friday night, no pretty bow to tie up the one loose end in one of the greatest rivalries the sport has seen. And yet, they stayed, rocking the rafters inside Arthur Ashe Stadium, chanting and cheering and singing his name.

It just wasn't the name anyone expected to be on the lips of thousands of lingering fans more than an hour after a much-anticipated quarterfinal match between Roger Federer and Juan Martin del Potro had ended. At majors, the 19-time Grand Slam champ brings the noise. It follows him from Melbourne to Paris to London and takes the 7 train from Manhattan to Flushing Meadows.

But not this night, not at this tournament, where the del Potro devotees have carried him through the flu, over a fever and back from a two-set deficit in the fourth round. And that was before helping him deliver a 7-5, 3-6, 7-6 (8), 6-4 win in a quarterfinal match Wednesday that del Potro said he was just happy to play "against the greatest guy in history."

"It's amazing to see the crowd like this," del Potro said after the match. "Against Federer, is not easy to share the fan's love. He is a local around the world in every tournament. Tonight, the people want to see a great tennis match. It's great after all my wrist problems, to come back and see how much the love from the fans comes to me."

Wednesday night, del Potro did everything he needed to beat the "greatest guy." His serve was lethal, his forehand was punishing, and his backhand -- his Achilles' heel since undergoing three surgeries to repair ligament damage in his left wrist -- worked when he needed it.

"Juan Martin fought like a lion," Federer said. "He was better today, especially on the big points. He served well, had some big shots when he needed to. He did so much better tonight, and that's why he deserves to win."

For Federer fans, the loss was heartbreaking, robbing them of yet another opportunity for Federer-Nadal in New York. But for del Potro disciples, it was heartwarming. He's as likable a spoiler as you will find in sports, a gentle-giant giant killer with a Grand Slam title and the resolve of an underdog.

If it is possible to imagine a different outcome to Tuesday evening's Venus Williams vs. Petra Kvitova match, del Potro's win over Federer felt a lot like what it would have been like inside Ashe had Kvitova taken the third-set tiebreaker. Sure, her win would have sullied the storyline of the all-American semifinal, but fans would have embraced the subplot of Kvitova's comeback from a horrific injury in lieu of a Williams win.

Like del Potro, Kvitova is one of the most well-liked players on tour and a sentimental favorite since beginning her comeback at the French Open. Like Kvitova, del Potro has battled back from a near-career-ending injury, one that taxed his mental game as much as his backhand. The glaring difference between the two, of course, is del Potro doesn't have to imagine what it would be like to upset the US Open favorite and charge ahead toward the semis.

"I am playing Roger in the biggest stadium of the tour in my favorite tournament," del Potro said. "It's a pleasure for me to be there, so I try to enjoy the tennis moment. Tonight, I play just free. I don't have anything to lose against Federer. I did my best game of the tournament tonight, and I play very smart during the whole match. It is so important to me, beating him another time in this amazing tournament."

A few years ago, struggling with pain and frustrated with his recovery, del Potro considered retirement. Monday night, fighting through the flu and down 6-1, 6-2, he considered retiring from the match. In both instances, he chose to keep fighting, and now here he is, two wins away from a second US Open title.

In 2009, he beat Nadal and Federer back-to-back to win this event. His wins against Dominic Thiem and Federer this year seem no less significant, and Nadal looms in the semis Friday night.

"When you play semifinals on a Grand Slam, anything can happen, so you must be ready for the chance," del Potro said. "But playing against Rafa in my favorite tournament, I will try to enjoy. If I play my best tennis, I know I could be a danger for him."