“He has the heart to challenge the top players.”
Jim Courier, who has first-hand experience facing elite contemporaries, chose these words to describe Juan Martin del Potro after the Argentine beat Roger Federer in a final-set tiebreaker to win this year’s Indian Wells Masters. Del Potro also saved three match points in the dramatic victory, his fourth over Federer in six final-round encounters.
Courier could be accused of cliché, but doing so would diminish the achievements of today’s top players—Federer, Rafael Nadal, Novak Djokovic—as well as del Potro, their kryptonite, foil or friend depending on the day. In this era of men’s tennis, one utterly dominated by an exceptional few, internal belief is as important, if not more so, than anything tangible on the outside.
But it doesn’t hurt to complement heart with the hardest forehand in the game. Or with one the sport’s most vocal fan bases, a traveling phalanx that rivals even Federer’s Swiss-flag-wearing army in intensity. Just ask Federer, who has been on the receiving end of both more times than he’d care to remember.
“Many fans give me too much love on court, off court as well,” del Potro said this March in Indian Wells, after winning his first Masters trophy.
“This is what I miss when I was injured.”
Moments before his fourth-round match against Dominic Thiem at last year’s US Open, a weary del Potro looked up from his chair. His field of vision was engulfed in blue and white: clouds dotting an azure afternoon sky; swaths of Argentina soccer jerseys among the teeming crowd.
The fans’ anticipation was palpable. They had seen del Potro’s peak at the same event eight years earlier, when a 20-year-old turned tennis on its head with an impressive display of might. On that day, the 6-foot-6 baseline bruiser was David, and he slayed Goliath Federer, who was attempting to win his third straight Grand Slam title and sixth consecutive US Open. In five sets, del Potro backed up his semifinal drubbing of Nadal by winning his first major.
“He played a great match,” Argentine legend Guillermo Vilas, watching that day, told Christopher Clarey of the New York Times. “He will win many more.”
Ever since, del Potro’s loyal armada has watched their hero try, and fail, to reach such heights. It was not for a lack of effort, but for injuries, sports’ cruelest element of randomness.
Del Potro’s wrist troubles began shortly after winning the US Open and lingered like an unkempt closet—try as one might to clean it out, it inevitably gets messy again. His first surgery, in 2010, was on his right wrist; after reaching the fourth round of that year’s Australian Open, he was out until the fall. The next three were on his left. In 2014 and ’15, a stretch that saw del Potro in nearly as many hospitals as tournaments, he would play a total of only 14 matches. He endured enough physical pain and spirit-sapping setbacks that he considered retiring.
“It’s been horrible for me,” he lamented at the 2015 season-opening tournament in Sydney. “One doctor would say something to me; another would say something different. It was difficult to believe one or the other.”
Del Potro’s once-promising career was a mess, but his off-court persistence would pay off. In June 2015, Dr. Richard Berger, an orthopedic surgeon who specializes in wrist care at the Mayo Clinic in Rochester, MN, prepared the 26-year-old for yet another surgery. The two had gotten to know each other well over the prior two years. This time, there was cautious optimism—and rightfully so. In February 2016, with a ranking of No. 1,041, del Potro returned at the Delray Beach Open, and he hasn’t missed extended time since. Berger and del Potro remain close friends.
But something was still holding del Potro back: his backhand. He could blast his signature forehand without issue, but all the left-wrist operations made his two-hander harder to strike.
“It was a little pressure for me to try not to miss easy forehands or not make double faults,” del Potro said after winning his first match back in Delray, “because I have to keep working and improving on my backhand to compete at this level. I think I’m in the middle of the process to solve the problem with my backhand.”
In addition to setting up his forehand, del Potro’s backhand keeps his opponents at bay with smooth, reliable power. Nowhere was that more evident than in the 2011 Davis Cup final, when del Potro—buoyed by a traveling corps of Argentines in Seville, Spain—nearly pushed Nadal to five sets on clay.
The answer to del Potro’s two-handed problem was twofold. First, develop a capable one-handed slice. And second, hit a lot of forehands.
Del Potro did both, to great effect, in 2016. He beat Djokovic in the first round of the Olympics and Nadal in the semifinals to clinch a second career medal. He reached the quarterfinals at a Slam for the first time since 2013; he won his first final in nearly three years; he beat Andy Murray in a five-set Davis Cup semifinal match in Scotland. To top it off, the Tower of Tandil gave Argentina its long-awaited Davis Cup when he rallied from two sets down to beat top Croat Marin Cilic in Zagreb.
“He’s a threat anywhere,” Martina Navratilova says of del Potro, who since returning has reached the French Open semifinals, Wimbledon quarterfinals and the US Open semifinals.
Returning to the US Open semis last year seemed unlikely after two lopsided sets with Thiem. While the Austrian’s spin-laced ground strokes were helping him gobble up games, del Potro was listless and ailing.
“Then I saw the crowd waiting for more tennis, waiting for my good forehands, good serves,” del Potro remembered. “I took all that energy to change in a good way, and thought about fighting and not retiring.”
If you want to truly impact a sports contest from the sidelines, consider cheering for del Potro. Rejuvenated by his longing supporters, he won the third set, 6–1, then saved two match points in the fourth with aces. He forced a fifth with a searing forehand winner that recalled his halcyon days.
The fans were delirious. But it wasn’t just old faithfuls that helped push del Potro past Thiem—it was his steadily improving backhand. “I made my best backhands of the tournament in the important moments of the match,” del Potro said after the battle. “It’s a good signal for the future.”
Two days later, in a tight four-setter, del Potro defeated Federer for the second time at the US Open; he saved four set points in a third-set tiebreaker.
Courier, who hit as many forehands as possible to hide his unorthodox, baseball-grip backhand, points to del Potro’s adjustments as a reason for the 29-year-old’s return to the top.
“He’s been able to overcome some of the wrist problems, make the backhand more of a neutral shot,” says the four-time Grand Slam champion. “He doesn’t have to slice it quite as much as he was slicing when he initially came back from left wrist surgery.”
Another reason for del Potro’s successful second act—in June, he equaled his career-high ranking of No. 4—has been his play against top players, particularly Federer. While he’s 7–18 against Federer overall, he’s 6–7 in matches that have gone to a final set. Two of those six wins were in Basel, Federer’s hometown event.
“He put himself out there with no double-hander almost, but just happy to slice and still take losses,” Federer said after his loss to del Potro in this year’s Indian Wells final. “But he was happy enough playing this way, which I admire a lot.
“It’s a great story. That’s why I’m also very happy for him.”
Del Potro's two deepest runs at the US Open include wins over Federer—in the 2009 final (first image) and in the 2017 quarterfinals, one match after surviving Thiem (third image) in thrilling fashion.
The rivalry between Federer and del Potro may be friendly, but it’s also brought out some of Federer’s greatest frustrations. In the 2009 US Open final, the mild-mannered Swiss was caught cursing at umpire Jake Garner after a late del Potro Hawk-Eye challenge. At this year’s BNP Paribas Open, Federer grew agitated by del Potro’s complaints about the crowd, which was making noise in between serves. It was an edgier side of both men, but in context, not an unfamiliar one.
“Should I have won the  US Open finals?” responded Federer to a question about his 2–4 record against del Potro in title matches. “I could have, should have. I don’t know. I didn’t. Same today.”
The always-humble Argentine has another explanation. “I like to play finals against him,” del Potro said later that same day, “because [I have] nothing to lose.”
Their rivalry may not have the sizzle of Federer-Djokovic or the stakes of Federer-Nadal, but Federer and del Potro have given us instant classics for nearly a decade, with no end in sight. Federer’s five-set survival at the 2009 French Open, with Nadal conspicuously absent from the final four, may be his most important win over del Potro; a 19–17 third-set triumph in the 2012 Olympic semifinals at the All England Club is also in the discussion.
Given Federer’s resistance to clay and the short grass season, hard courts are where the next chapters of this rivalry—one of tennis’ best—will unfold. All of del Potro’s wins over Federer have come on the inflexible surface, and he holds an unmistakable edge over him at the US Open.
“Beating him another time in this amazing tournament,” del Potro said last year, “is so important to me.”
Whomever del Potro faces in New York will be tasked with one of tennis’ tallest orders. At Wimbledon, Nadal needed five sets to beat del Potro and his 107-m.p.h. forehand. In this era of men’s tennis, there’s the Big Four; but in terms of size, shots and heart, it doesn’t get much bigger than del Potro.