Watching Juan Martin del Potro the last few years became an exercise in wondering what might have been.
Starting with the 2005 French Open and running through the 2013 U.S. Open, Del Potro was the only man to win a Grand Slam event other than the "Big Four" of Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray. There was every reason to believe the 6-foot-6 Argentine player would expand that group to five. But debilitating hand injuries and four surgeries — three on his left wrist and one on his right — robbed him of the strength that fueled his ballistic two-handed backhand and had positioned him for greatness after his memorable 2009 U.S. Open victory over Federer. Between the third and fourth surgeries, in January 2015 and June 2015, Del Potro became discouraged enough to ponder retirement.
He came to realize that to have any chance at competing at the highest level again he would have to change his game and his mindset. Without his old power, he'd have to become crafty. Without sheer force he would have to go to the net more often, mix in slices and drop shots and otherwise vary his game. It was not a tradeoff he would have made if he'd been given the choice.
"Of course no," he said. "Because with my old game, I won the U.S. Open. I was No. 4 in the world. But with this way of play, I win. I won different things and important things, too. And I think is the only way, if I want to keep playing tennis. And I deal with that every day and accept the conditions of my wrist or my body."
Now, instead of mourning what he might have done if not for his bad luck, Del Potro has given his legions of fans — which means just about anyone who has met the genial Argentine player, played against him or watched him unashamedly cry on the court — reasons to rejoice over what still might be.
Despite looking lost Wednesday night in the first set of his round-of-16 match against friend and Davis Cup teammate Leonardo Mayer at the BNP Paribas Open, Del Potro crafted a 3-6, 7-6 (2), 6-3 victory that even he couldn't fully explain. Seeded No. 6 and ranked eighth in the world after having fallen to 1,045 barely two years ago, he sliced and diced and willed his way into a quarterfinal match Friday against Philipp Kohlschreiber of Germany, who was a 6-4, 7-6 (1) winner over Pierre-Hugues Herbert of France.
How did Del Potro turn around what threatened to become an embarrassing loss and turn it into his eighth consecutive victory, delighting a crowd that lived every point with him and frequently chanted his name?
"I don't know," he said, smiling. "But I did."
The second chapter of his tennis life has become a lot more enjoyable than it was a few years ago. This year, he has made it to the final in Auckland, New Zealand, and won his 21st title, in Acapulco, beating top-10 players Dominic Thiem, Sascha Zverev and Kevin Anderson in a row. Here, he defeated wild-card Alex de Minaur and No. 29 seed David Ferrer before prevailing over Mayer, a longtime friend and co-Davis Cup champion.
When he and Mayer embraced on the court at Stadium 1 on Wednesday night, Mayer rested his head on Del Potro's shoulder for a moment. Everyone in the crowd would have loved to do the same, to pay back some of the joy he has given them over the years.
Del Potro, 29, won't get his old game back. But he's embracing this exhilarating renaissance.
"Yes, yes, of course I didn't expect to get in the top 10 again. And I won titles again, and I got the silver medal in Rio playing one of my best week of tennis on my life," he said of the 2016 Olympics. "All these things happen after my surgery."
Del Potro couldn't find his range with his forehand in the first set Wednesday, and Mayer broke his serve for a 5-3 lead and won the set when Del Potro netted a return. Mayer broke for a 2-1 lead in the second set but Del Potro broke back on his second chance and they stayed on serve, setting up the tiebreaker.
"I think I was very smart during the tiebreak," Del Potro said. "After then, I turned around the match and the control of the points, and then I start to play much better right after the tiebreak."
Del Potro got a break in the first game of the third set and was able to get his forehand dialed in well enough to close things out by breaking Mayer in the final game. He has become a force again, and tennis is better off for his presence.
"Of course, I cannot believe what I'm doing in my 'new career,' you know. But I'm enjoying a lot," he said. "I just enjoy the tour more than few years ago. And I like to be here because this is my job and this is what I love."