When he was just one point from finding himself down a match point, Alexandr Dolgopolov received a Juan Martin del Potro serve to his forehand with a characteristic ploy. He took a savage sliced cut, but at such an extreme angle that the ball—if it went over—would have been a wildly spinning, “Bend It Like Beckham” semi-drop shot.

It was all academic, though. The ball did not go over. It hit the very top of the net, stopped for lunch, rolled along a bit and finally dropped back on Dolgopolov’s side of the net. The Ukrainian turned to his guest box, which contained his father-coach, Oleksandar, and grinned as if in appreciation of the shot—or more likely a premature show of disbelief in how he had managed to lose the match. The result became official two points later, as del Potro advanced, 1-6, 6-4, 6-3.

This match-up is by nature entertaining, because it pits a big, strong, physical man who plays the most elemental bread-and-butter game against one of the most energetic, volatile, and unpredictable shotmakers in tennis. Del Potro is a cake without frosting; Dolgopolov is frosting without cake.

For a long time in today’s two-hour clash, it appeared that for once, Dolgopolov would not just start strong but finish that way as well. He had break points right off the bat in the first game, although del Potro managed to hold after eight-plus minutes. But after that, it was all Dolgopolov. He mixed unreachable drop shots with fierce backhand service return drives (del Potro would win just 34 percent of his second-serve points in the match) and forehand blasts hit with such energy that, as he made contact, Dolgopolov looked like a bug hitting the windshield of a car traveling at 125 M.P.H. That he could take del Potro’s serves three and four feet inside the baseline was eye-opening.

Granted, del Potro himself looked sluggish and defensive from the outset. But he began to turn it around early in the second set, earning an early break. But Dolgopolov broke right back. Sustaining his first-set level, Dolgopolov seemed to take control for good when del Potro wasted a 40-love lead in the seventh game and ended up broken. The key shots from deuce were a pair of inside-out forehands—the first during a rally, the second a second-serve return winner. Now it was 4-3, Dolgopolov leading, with serve.

In that next game, Dolgopolov jumped out to a 30-love lead. But then the wheels came off, and spectacularly so. He failed to put a first serve into play for the rest of the game, and lost it in short order with a double-fault followed by three groundstroke errors. The collapse was as spectacular as his early match shotmaking had been.

Dolgopolov won the first two points of the next game, though, and ultimately held three break points against del Potro’s serve. But the No. 5 seed served his way out of two of them and teased out a forehand error on the third. Del Potro went on to hold the game and go ahead, 5-4, and he celebrated the lead with a break that won him the set.

The first few games of the third set were played in a surreal shroud of near silence, as the fans began to drift away for the evening, leaving the two players stuck like contestants in a tractor pull. Neither could move the other, their wheels digging deeper and deeper into the red clay, until del Potro broke a subdued Dolgopolov in the fourth game to take the lead, 3-1.

When Dolgopolov broke right back, it looked like he might have wiped away the memory of losing that second set, but his respite was temporary. He played a terrible game featuring a pair of ill-chosen and unsuccessful drop shots and was broken in four straight points. All del Potro needed to do after that was hold his serve twice, and he managed that task better he did earlier on a day that did not exactly bode well for his long-term chances at this tournament.

Stat of the day: Dolgopolov managed to put just 36 percent of his first serves into play.