Thus far in this U.S. Open, Grigor Dimitrov has been able to sustain his momentum, with all of his physical talents fully on display.

It was once expected that Grigor Dimitrov, the 28-year-old from Bulgaria, would have been rather familiar with playing into the later stages of a major, something he’s accomplished at this year’s U.S. Open. But as the former world No. 3 prepares for what could be the most important match of his career, against Daniil Medvedev in the semifinals today, he enters the contest keenly aware of how humbling the life of a professional tennis player can be—while also looking at his best opportunity yet to claim a Grand Slam title.

Dimitrov started this year’s tournament facing Andreas Seppi, ranked one spot ahead of him, at 77, in the ATP Tour standings. The 35-year-old Italian was the heavy favorite to win; after all, over the past year and a half, on-court struggles and health woes had led to a precipitous fall in the standings for Dimitrov, whose potential as a future world No. 1 was hardly in doubt early in his career. Times, though, had changed: Earlier this summer, he lost to a player ranked outside of the top 400.

Somehow, after splitting the first two sets with Seppi, Dimitrov closed out the match in four to post one of his most solid victories of the year. From there, he’s been able to sustain his momentum, with all of his physical talents fully on display. Dimitrov’s one-handed backhand is picturesque, and he can strike it with pace, drive it with top spin, or slice it from any position on the court; his forehand is a weapon on any surface, and he can deliver his serve with unerring accuracy. Dimitrov possesses both the instinct and the exquisite touch necessary for success when up at the net. His game is also uncannily similar to that of the all-time leader in men’s Grand Slam singles titles, Roger Federer. After a five-set victory in the quarterfinals over the Swiss—whom Dimitrov had never defeated in seven prior matches, and to whom he’s been compared for the bulk of his career—he now has another chance to reach his first Grand Slam final, after having advanced to only two other semifinals before: at Wimbledon in 2014 and at the Australian Open in 2017.

Standing in his way this time will be Medvedev, the fifth-ranked player in the world. The 23-year-old from Russia has reached three straight finals this summer and is riding an 11-match win streak. Where Dimitrov’s game is built around an all-court attack, Medvedev presents a matchup problem “because his ball seems easy to play, but it’s really, really tough,” Medvedev’s coach, Gilles Cervara, recently said, adding that “he covers the court so well and his mentality is getting stronger and stronger.”

During this tournament, Medvedev’s sometimes hostile interactions with the New York crowd have often overshadowed his on-court accomplishments. In his past two matches, his health has been an issue, as he’s been forced to deal with the stress of playing deep into the draw of his past four tournaments, including the U.S. Open. By contrast, Dimitrov, who will be playing in his first semifinal of the year, should be the fresher of the two as he tries to go a step further than when he was last in this position, two years ago.

That semifinal result, back in Melbourne, was part of a near-perfect start to the year for the Bulgarian. He won two of his first three tournaments, with the only loss coming in the penultimate round at the Australian Open to Rafael Nadal in a seesaw five-set affair. In the second half of the year, Dimitrov won the hard-court title in Cincinnati, which bumped him into the top 10 for the first time in three years, and the ATP Finals, which made him No. 3 in the world, behind only Nadal and Federer. With the other two members of the “Big Four”—Andy Murray and Novak Djokovic—battling injuries, Dimitrov was in a position to improve his place in the standings. After some solid early-2018 results, though, a months-long slump took hold: From April to the end of the year, Dimitrov reached only one semifinal. He maintained his place in the top 10 throughout the majority of 2018, but being unable to defend his title at the ATP Finals knocked him from that perch and he finished the year at No. 19.

Eager to turn things around, Dimitrov enlisted one of the greatest male players in the history of the sport to join his team. Andre Agassi, whose only other coaching stint came with Djokovic, started off 2019 committed to aiding Dimitrov. The excitement generated by such a pairing was limited nearly from the onset of this year, as a shoulder injury sidelined Dimitrov for two months. After losing to the young American Frances Tiafoe at the Australian Open, Dimitrov didn’t play again until the Miami Open, where he was upset by the world No. 77, Jordan Thompson.

During the clay-court season, Dimitrov fell out of the top 40 in the rankings, and further struggles left him outside of the top 75 for the first time in seven years, setting the stage for his battle with Seppi. Winning that match brought a halt to a three-match losing skid for Dimitrov, and he went on to stop Poland’s Kamil Majchrzak in the third round after being granted a walkover in the second. In the fourth round, Dimitrov faced Australia’s Alex de Minaur, who has been hailed as one of the sport’s brightest prospects—a position not unfamiliar to Dimitrov—but de Minaur was unable to mount a challenge against his more experienced opponent. “There’s not much to say other than that I’m pleased to be back on a court pain-free and feeling really good,” Dimitrov said after that match.

Into a tournament quarterfinal for only the second time this year, Dimitrov faced Federer, who had only ever dropped two sets against his stylistic counterpart. After Dimitrov lost the first, another victory appeared to be in line for the Swiss. However, the resolute Dimitrov soon leveled the match at a set apiece; Federer then went up two sets to one, but in battling both a game opponent and his own body, he eventually fell in five, sending Dimitrov through to the semifinals.

Dimitrov and Medvedev haven’t faced each other since 2017, when they split a pair of matches over the summer, with Dimitrov winning on grass and Medvedev emerging on top at their sole hard-court encounter. If Medvedev were to win this match and go on to take the title, he’d join his countrymen Marat Safin and Yevgeny Kafelnikov, former world No. 1s and inductees into the International Tennis Hall of Fame, as the only Russian men to win Grand Slam singles championships. Medvedev will also reach a career-high No. 4 in the rankings, regardless of how he performs the rest of the tournament.

For Dimitrov, a championship would carry its own special meaning. Aside from becoming only the third player this decade to win a Grand Slam singles title aside from Djokovic, Nadal, Federer, and Murray, it would bring him closer to the upper echelons of the sport once again. As the tennis writer Joel Drucker recently wrote after Dimitrov’s win against Federer: “We shall see soon if this evening was the first day of the rest of Grigor Dimitrov’s tennis life.” Two years ago, Dimitrov appeared to be ready to fulfill all of the expectations heaped upon him. Now the Bulgarian—brimming with confidence—is poised to meet them head-on once again.

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