It'll be a U.S. Open semifinal rematch for Dominic Thiem and Daniil Medvedev on Sunday with the ATP championship on the line.  

Medvedev stormed back to defeat Rafael Nadal 3-6, 7-6(4), 6-3 in the semifinals on Saturday as the 24-year-old Russian took down the Spanish star for the first time in his career. Now Medvedev prepares for a quick turnaround against Thiem after the two put on an incredible duel at UTSA Billie Jean King National Tennis Center in mid-September. 

Thiem won that round in three hard-fought sets 6-2 7-6(9), 7-6(7) before defeating Alexander Zverev in five sets to claim the U.S. Open—the Austrian again rallying back after dropping the first two sets to Zverez.

He required that same focus to take down No. 1 seed Novak Djokovic earlier on Saturday, 7-5, 6-7(12), 7-6(7). 

"Dominic is playing amazing right now," Medvedev said Saturday. "Already in the US Open when I lost against him, after the match, I was sitting in the locker. I was like, 'I was playing good this match', but he managed to do it, won his first Grand Slam. I practiced also the first two times on center court with him. We had good rallies, a really good level of tennis. I said to my coach, he can go far here.' I don't know if he said the same."

It's the second consecutive year Thiem has reached the ATP final, but he's still looking for his first title after falling to Stefanos Tsitsipas in 2019. 

Medvedev is making his first appearance in the ATP final after emerging from a group play stage that featured Djokovic, Zverev and Diego Schwartzman. Medvedev went a perfect 3-0 during group play, defeating each opponent in two sets. 

That led to a semifinal on Saturday where the Russian figured out how to stop Nadal.

Medvedev picked up 13 aces, won 105 points to Nadal's 94 and won 77 percent on his first serve. Nadal was nearly powerless down the stretch after dropping the second set. 

"I felt really strange till 5-4 for him in the second set. I felt like I was doing great shots, but I couldn't return, make a good shot in the important moments.," Medvedev said on-court afterwards (h/t Tennis.com). "I decided to change some small things, going for it a little bit more. I felt like I had chances to win before, some games, a set maybe but it didn't work. So I had to change it and it worked really well. I'm happy about it."