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.

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 today with a semifinal place at stake. Nadal has never won the ATP Finals, one of few gaps on his resume.

(SD-Agencies)