Novak Djokovic is two wins away from his sixth career ATP Finals championship.
The top seed in the tournament advanced to the semifinals with a 6-3, 7-6(4) victory over No. 5 Alexander Zverev in the first match of the day.
Djokovic won this event four consecutive years from 2012-15, tied with Ilie Nastase for the longest streak in ATP Finals history. He did reach the final in 2016 and 2018 but lost to Andy Murray and Zverev, respectively.
Zverev has been one of the few players on the ATP Tour with success against Djokovic. The German star entered Friday's match with a 2-2 record in their previous four head-to-head matches, but cost himself a chance to move ahead in their rivalry with a number of self-inflicted mistakes.
On the list of mistakes for Zverev were six double-faults. He was also unable to take advantage on any of the three break-point chances when Djokovic was on serve.
Zverev did show plenty of fortitude throughout the match, including finally getting the better of Djoker during this long rally in the first set:
The second set was a close back-and-forth affair between the two stars. Zverev had an opportunity to force a decisive third set if he could have won the tiebreak, but Djokovic was able to pull ahead at the end and secure his spot in the semifinal.
Djokovic will take on Dominic Thiem in the first match on Saturday. Rafael Nadal and Danill Medvedev will meet in the second semifinal matchup.
Medvedev, who already locked up his spot in the semifinal after beating Djokovic on Wednesday, had no problems getting past No. 8 Diego Schwartzman 6-3, 6-3.
The 6'6" Russian is wrapping up his 2020 season in style with eight straight match wins dating back to the Paris Masters two weeks ago. He had a 4-0 advantage in aces against Schwartzman and saved all of his break points to get the win.
Next up for Medvedev will be his biggest test of the tournament. Nadal has won each of their three head-to-head matchups, all of which came in 2019. Their most memorable encounter was a five-set marathon at the U.S. Open final that took nearly five hours to complete.
This is one of the few events Nadal has never won in his historic career. He's lost in the final twice (2010 and 2013).
Medvedev can erase those bad memories against Nadal on Saturday if he can pull off a win and advance to the final of the last ATP Tour event of the year.