When it was over, the spectators at Arthur Ashe Stadium chanted his name, “Ruuuuud!” — and it sounded like they were shouting, instead of greeting. Rudd, runner-up to Rafael Nadal at the French Open in June, is a 23-year-old from Norway who can move from No. 7 to No. 1 by winning the championship at Flushing Meadows on Sunday. “After Roland Garros, I was, of course, extremely happy,” Rudd said, “but also humble enough to think that this could be the only final of my career.” Well, here he is, back at this stage just a few months later. His opponent in this Sunday’s final will be No. 3 Carlos Alcaraz of Spain or No. 26 Frances Tiafoe from the United States. Like Rudd, Alcaraz went into Friday with a chance to move up to replace 2021 US Open champion Daniil Medvedev at the top of the rankings after the tournament. All four men’s semifinalists made their New York debut at this round. This hadn’t happened in the event since 1881, when it absolutely had to: This was the inaugural edition of what was then known as the US Championship. Rudd is coached by his father, former pro Christian, and the game plan worked flawlessly for most of the day against the 31st-ranked Khachanov, a 6-foot-6 Russian with a powerful serve who eliminated Wimbledon runner-up Nick Kyrgios in five sets in the quarterfinals . To mitigate the effect of Khachanov’s serves, Ruud would stand far back from the baseline to return and then try to dominate exchanges from the baseline. Rudd used flawless side-by-side defense football and found openings to deliver deep ground moves that could end points. He arrived with occasional flashes of brilliance, such as the over-the-shoulder volley winner that put him 6-3 ahead in the tiebreak. Moments later came match point, Rudd’s third chance to end the set. It lasted 75 seconds and featured 19 more strokes than the second-longest rally of the fortnight, culminating in a backhand from Ruud that netted a forehand in response. Dad smiled. His child raised both his hands and held up two fingers on his right hand. It could have just been the pointer to indicate No. 1, which could be next to his name soon. Khachanov couldn’t recall a 55-shot rally in his career, and although he hated to lose it, he was initially encouraged afterwards by the way he played at the end of the set. “I felt like we had this long rally, we were both moving forward,” he said. “I felt like, ‘OK, it hurts to lose a set by that point.’ On the other hand, I felt like, “Okay, now we’re going a long way, let’s keep going.” Ruud broke back to go up 2-1 in the second set and was on his way there. After Khachanov surged late in the third to make things a little more interesting, Ruud broke to take a 2-1 lead in the fourth, ripping a forehand winner from the deuce line. This marks the latest step in a real move forward for Ruud in the Grand Slam game. He entered this year with just a 14-13 record in the sport’s biggest events — 3-4 in New York, where his previous best showing was a third-round appearance in 2020 — then had to sit out the Australian Open January after twisting his ankle in training the day before the tournament began. Since then? He is 13-2 in the major leagues in 2022.