The moment that changed Daniil Medvedev's career -- and led him to the US Open final

Medvedev headed to finals after straight-sets win (1:26)

Daniil Medvedev defeats Grigor Dimitrov 7-6, 6-4, 6-3 to advance to his first career Grand Slam final. (1:26)

NEW YORK -- The day before Friday's US Open semifinals, Daniil Medvedev was out on the National Tennis Center's P3 practice court, wearing a black T-shirt with the imprint of a neon-blue alligator, with Japan's Haru Inoue across the net. They were doing a drill in which both men kept hitting crosscourt, each of Medvedev's crisp shots punctuated by a soft grunt, "Eh ... eh ... eh."

Suddenly, Medvedev would rotate his torso, adjust his stance and swing, sending the ball like a rocket down the line. This ability to change the course of the rally, called "redirecting," is critical for success in today's game.

Medvedev's talent for changing course in the blink of an eye goes far beyond the practice court. Just two years ago, he was a talented but callow 21-year-old, ranked outside the ATP top 50, uncertain he wanted to put in the work it takes to perform at the elite level. He lost in the first round at the 2018 US Open. But on Sunday, Medvedev will face Rafael Nadal for the trophy, the first player under 23 to reach the US Open final since Novak Djokovic in 2010.

Call it a course correction. It all started in January 2018, just weeks after the Moscow-born youth hired a full-time coach, Gilles Cervara. The two met when Medvedev left Russia seeking higher-quality coaching and settled in the south of France, where his sister lived. In Cannes, he worked with various mentors until he and Cervara made an exclusive pact in late 2017.

The major area of concern for Cervara was Medvedev's history of succumbing to frustration and anger. As a junior player, he sometimes got into screaming matches with coaches and others on the sidelines. At Wimbledon in 2017, he threw coins at the base of the umpire's chair after a second-round loss.

"I actually have no idea why all the demons go out when I play tennis, and especially when I was a junior," Medvedev said after his semifinal win over Grigor Dimitrov on Friday. "I had a lot of problems with my attitude."

Cervara had hoped to help Medvedev control his emotions on the court, but they got off to a rough start. In his first tournament of 2018, Medvedev stumbled out in the opening round of a Challenger event, the tennis equivalent of Triple-A baseball.

"The match was very bad," Cervara told ESPN.com. "We fought together during the game. I was mad. I was trying to help him, but mad at his behavior. After he lost, we had a talk, and at that moment we started to build something else. His tennis identity started to grow up at that point."

A week later, Medvedev was on the court against Alex De Minaur in the final at the Australian Open tuneup event in Sydney. In the third set, Medvedev allowed hometown favorite de Minaur to recover from a two-break deficit to tie things up 5-5. Instead of giving up, Medvedev kicked himself into high gear and won 7-5.

"Probably two years ago, I would just have said, 'No, I don't want this anymore.'" Medvedev told reporters afterward. "But I managed to win it. My first title. It gave me a big push."

"It was a great win for us," Cervara echoed. "It showed our process is working."

Since then, Medvedev has won four more titles, including the prestigious Cincinnati Masters in August. Among his Next Gen cohorts, only Alexander Zverev has won more, and Medvedev has leapfrogged over him in the rankings.

At 6-foot-6, Medvedev is built like a pencil, but this summer he has been erasing his opponents. Logging 20 hard-court wins in the span of a mere 32 matches is an impressive feat of mental and physical stamina. He leads the tour in wins (50) and finals (six) and is 2-4 in those title matches. Only two other men have reached the finals in the four big summer events: Ivan Lendl and Andre Agassi. No wonder Medvedev boasts about sloughing off his younger, slacker self.

"I changed it," he said. "I've changed myself on the tennis court."

Medvedev hasn't buried his emotions, as he demonstrated during the first week of this tournament when he taunted and sparred with the New York crowd. But unlike some of the game's other volatile personalities, he has become a model of consistency. He credits his wife, Daria, his coach and his sports psychologist for helping him control his temper and focus on the court.

Cervara describes Medvedev as a "genius," and their connection is powerful.

"It's really tough to explain how we communicate together," Cervara said. "Sometimes you don't explain, you know. Sometimes with people you don't talk. It's just energy between two people. It's [a] look [between] two people. It's more like this."

The only other team member to travel to New York this fortnight is Medvedev's sports psychologist, Francisca Dauzet. A composed, soft-spoken woman with an easy smile, she often meets with Medvedev multiple times a week.

"It's not magic, and I'm not a guru," she said in an interview. "He's rising now, but it is over one year we are working together. He has improved about this kind of [mental] work."

Medvedev agreed.

"She's helping me a lot," Medvedev said of Dauzet. "I was sitting after these matches and I was like, I don't want to lose matches because I got crazy or because I lose concentration because of the fans, because of the referee. I want to lose tennis matches because I was a worse tennis player than my opponent."

Dauzet said that her work is informed by an interest in Chinese medicine, meditation and the philosophy of the Shaolin Warriors, an order of Chinese monks famous for cultivating one of the oldest and most respected forms of kung fu. She would like for Medvedev to achieve the same inner calm and sensory awareness.

"When a Shaolin fights, he never even looks around," Dauzet said. "He just feels the things going on."

When it comes to Medvedev's talents, though, she leaps from ancient China into the digital age.

"His mind is very big," she said. "It is very complex, like a computer, it has many things and he can join all the points in one second."

It's an apt analogy, because Medvedev might already be unrivaled as a problem solver. He went into his fourth-round match against qualifier Dominik Koepfer planning to hit flat and force his opponent, who surely would be nervous, to make unforced errors. It didn't work out that way.

"He was playing all the lines. He was destroying me," Medvedev said after the match. "It was 6-3, 2-0 [for him]. I just didn't know what to do. I did something I would not be capable of one year ago. I started playing as aggressive as I could, taking the ball as early as I could, which I usually don't do. That's why I won, and that's why this victory is even more precious."

That was pure Medvedev, an expert on altering the terms of engagement, mixing purring topspin semi-lobs with flat, rifle-shot forehands -- serving rockets one moment, off-speed marshmallows the next. And all the while, he shuffles around looking tuckered out, a thatch of unruly brown hair flopping at an angle over his prominent forehead. Some of his peers change shirts six or eight times during a match. Medvedev doesn't change once. It isn't because he can't afford it.

Medvedev will seek to snatch his first Grand Slam from the hands of a man who owns 18, Rafael Nadal. They've met only once, with Nadal thumping Medvedev in the Canada Masters final just weeks ago, 6-3, 6-0.

"It was a tough one," Medvedev admitted. "Rafa's energy was much higher than mine. ... I had one break point, then he got a break, then he was only going harder, harder, faster, stronger -- and I was only going down."

However, Medvedev said he was happy to have had at least one experience of Nadal's unorthodox game to prepare him for this meeting. It's time for Medvedev to contemplate another change of course.