Thiem, Tsitsipas take matches in ATP Finals

London — Dominic Thiem mastered the tiebreakers again to get the better of Rafael Nadal, and defending champion Stefanos Tsitsipas also won Tuesday on Day 3 of the ATP Finals.

Thiem beat the 20- time Grand Slam champion in straight sets and secured his spot in the semifinals when Tsitsipas outlasted tournament newcomer Andrey Rublev in the evening match at an empty O2 Arena.

Thiem clinched a 7-6 (7), 7-6 (4) win on his fifth match point in his first meeting with Nadal since the Australian Open quarterfinals in January, when the Austrian player prevailed after winning three tiebreakers in a tight four-set match.

“If I want to look for mistakes or for things I didn't do right, I think I wouldn't find many,” Thiem said.

The U.S. Open champion opened group play in the season- ending event with a three-set victory over Tsitsipas on Sunday and qualified for the semifinals when Tsitsipas won 6-1, 4-6, 7-6 (6), handing Rublev his second defeat.

Today, top-ranked Novak Djokovic will play Daniil Medvedev — both players won their opening matches — and Alexander Zverev faces Diego Schwartzman, with both in search of their first victories.

Nadal, who beat Rublev in straight sets in their opener, missed a chance to qualify with a match to spare and next will play Tsitsipas on Thursday with a semifinal place at stake. Nadal has never won the ATP Finals, one of few gaps on his resume.

Nadal credited Thiem but described the match as “very equal.”

“Both of us played at a very high level.

“He deserved to win because he played a little bit better at some key moments,” Nadal said.

“I am much more confident now with the level of tennis that I am playing than a couple of days ago.”

Thiem, who described his performance as one of the best of his career, won the first set after coming from 5-2 down in the tiebreaker, saving two set points in the process.

There was high-quality shot-making throughout the match, but not least when Thiem produced two inside-out forehand winners in a threepoint span to close the tiebreaker — the first on set point for Nadal — and then to clinch the set.

“It was a great match from the first to the last point,” Thiem said, “but actually I was pretty lucky to get that first set.”