ROME -- Jannik Sinner, the savior of Italian tennis, came into the semifinals at the US Open heavily favored. But he was going up against Jack Draper of Great Britain who had gone through five matches in a row without losing a set. Draper’s heavy lefthanded first serve gave him a puncher’s chance against any player, even the world’s #1. Draper stayed even with Sinner until 5-5, at which point he scattered three double faults amid a couple of aces. When he lost his serve, Sinner had only to hold his to win 7-5.

 The second set was equally close with neither man dropping serve. Draper packed plenty of muscle into his shots. His effort was obvious. He perspired profusely, and between points all during the match a ballboy had to hustle out to dry the court with a towel. If Sinner sweat, it wasn’t apparent. He seemed to generate easy power with his smooth strokes and whiplike follow through. There was a moment of uncertainty when he changed directions and fell hard on his left hand. He got up and grasped his wrist in pain and was treated by a medic. Although he fidgeted with that aching wrist for the rest of the match, he played on, easily winning the second set in a tie-break. This seemed to deflate Jack Draper who like so many opponents this year just couldn’t keep pace with Sinner over the long haul. Thus the Italian advances for the first time into the finals of the US Open, the only player from this countryto do so in the Open Era.
 The second semifinal between two Americans raised expectations at Flushing Meadows to the boiling point – which was only a few degrees hotter than the air temperature at night in New York. Taylor Fritz had a 5-1 record against Frances Tiafoe, but the match figured to be a toss-up. Although the two men were close friends, each was eager to be the first American to reach the US Open final since 2006. Languid and confident, Fritz arrived on court in what looked almost like a formal outfit by Hugo Boss, whose label stood out like a challenge.

 By contrast, Tiafoe was draped in purple duds by Nike which appeared to be sweat-stained from the start. He changed his shirt several times a set but stayed cool and poised enough to win the first set with deep, penetrating serves and viciously angled volleys.

  Fritz hung on to win the second set 7-5. That seemed to be a mere blip on Tiafoe’s part, a matter of a few poor choices. On a couple of points, he hit botched drop shots when he could have hit a winner cross court. In the third set he seemed to regain his form and outplayed Fritz 6-4 for a two set to one lead. Tiafoe looked to be in the driver’s seat. Indeed, he afterward admitted that he made the mistake of thinking ahead to the final against Sinner. Playing at the absolute top of his game, he had every prospect of tucking away the fourth set and the match. But then as he explained in the interview he experienced several spasms and feared he was cramping. His shots didn’t have the same depth or sting. Taylor Fritz sensed this and started to prolong the points. With the score 3-3, one of their exchanges lasted 31 strokes. After that, Tiafoe was never the same. Dominating from the baseline, Fritz evened the match at two sets apiece, running off eight points in a row.

  In the fifth set, Fritz remained in clear control while Tiafoe struggled. He had lost a step and never quite got his feet under him again. Over and over, he hit off balance, punching the ball into the net or sailing it long. Down 4-0, he finally broke Fritz’s serve, which gave his fans hope, but didn’t give Tiafoe the energy he desperately needed. He lost 6-1 and afterward in a press conference rejected the notion that that 31-stroke exchange in the fourth set had been the turning point. But he was as wrong-footed in his answer as he had been wrong-footed throughout the last set.

 In more good news for Italy, the Italian mixed doubles team of Sara Errani and Andrea Vavassori won the US Open title in straight sets.