“Everything is bad and black, a black mind.”

Those ominous words were spoken by Juan Martin del Potro in an interview with Sport 360 in Dubai earlier this week. The big man had reason, it turned out, to feel gloomy. Today del Potro, the tournament’s second seed, retired after losing the first set of his opening-round match to Somdev Devvarman. The cause was the traditional one with Delpo, his wrist. Four years ago, he had surgery to repair his right wrist; now he says he feels similar pain in the left one.

“I don’t feel really well,” a near-tearful del Potro said today. “My wrist is hurting a lot and everybody knows what happened to me four years ago with my other wrist. It was really tough to play today. I tried everything. I cannot be the player I would like to be.”

It’s hard not to feel for del Potro at times like these. He’s a showman, a fan favorite everywhere he goes, and is respected by his peers. Even after Delpo sent Andy Roddick into retirement at the 2012 U.S. Open, the American could still turn around and say, “You won’t find anyone who doesn’t think he’s a class act.” That includes Roger Federer, who helps represent del Potro at his new agency, Team8.

Just as important, the Argentine, while he’s 25 now, is the closest thing the ATP has to a long-term successor to the current Big 4. He seemed to be on the verge of breaking their chokehold on the game in 2009 when he beat Rafael Nadal and Roger Federer in succession to win the U.S. Open. But by the 2010 Australian Open, his right wrist was acting up; soon after, he underwent surgery and was forced to miss the entire season.

So far 2014 is looking, as Delpo seems to foresee, horribly familiar. After three years of work to get back to his ’09 best, he had finally arrived there at the end of 2013, when he beat Nadal and Federer and finished a career-high No. 5. As if on cue, del Potro’s left wrist began acting up at the Australian Open, where he was upset by unseeded Roberto Bautista Agut in the second round.

Is Delpo heading for a repeat of 2010? In February he flew to the Mayo Clinic in Minnesota, to visit the doctor who repaired his right wrist. So far the treatment this time has been physical therapy rather than surgery. Del Potro surprised a lot people, myself included, by returning to the tour two weeks ago in Rotterdam, where spent much of the event slicing his backhand because of the pain, and lost to Ernests Gulbis in straight sets in the quarterfinals. Now, after his defeat in Dubai, del Potro say he’s heading back to the Mayo Clinic.

“Everything goes in the negative way,” he told Sport 360. “But I believe in my doctor. That’s the doctor who fixed my right wrist, and I trust him.”

Del Potro apparently trusted him enough to play through the pain the last three weeks. You have to hope he didn’t also do it to keep the people counting on him happy—the tournament directors who pay him appearance fees and put him on their marquees, the agents that take a cut of those fees, the fans who want to see him play. It's tough for a top player to say no to a trip to Dubai, knowing how much money he and his management team will get just for showing up. It would also be understandable if Del Potro, who says his goal is simply to hang on to a Top-10 ranking this year, is hesitant to undergo surgery again and potentially lose another season of a career that he must feel is already speeding by rapidly. We’ll see what the doctor says this time; surgery or not, it’s hard to imagine that a break won’t be necessary.

When I think of other top male players who never reached their potential because of injuries, my mind goes back to Miloslav Mecir. The Czech won the gold medal in singles at the Seoul Olympics in 1988 and reached the final of the Australian Open in 1989, but was forced to retire in 1990, at age 26, due to a chronic back injury. Tennis history can be affected by these things. Thinking about Mecir, though, only makes del Potro’s ailment seem more ironically depressing. As he has said, you would expect a player his size—6’6”—to suffer from a bad back, but he’s mostly been healthy there.

Leave it to del Potro, even when “everything goes the negative way,” to find a way to give the fans something to see and applaud anyway. In his loss to Gulbis in Rotterdam, del Potro played the sad showman to perfect, comically depressing effect. After one of his slice backhands landed in the bottom of the net, he stood and shook his head for a long time at the court, as if to ask, “Why is this happening to me?” The crowd cheered him. A few minutes later, Delpo ran after a ball and ended up at the side of the court, a foot from the front row, where he put his head down for a theatrically long time. The crowd cheered again. Finally, at the end of the match, he challenged a line call. As he waited for the replay, he asked a fan whether the ball had been good or not. When the challenge went in his favor, del Potro shared a thumbs-up and a fist-pump with the fan. That day at least, he took his frustration with a smile.

Delpo can connect with a crowd, whatever the circumstances. Which makes it even tougher to see him leave the tour for the doctor’s office again. As a tennis fan, I can only hope he takes all the time he needs to get past the blackness, and get his wrist healed, for good.