Dominic Thiem beat Stefanos Tsitsipas in the opening singles match of the ATP Finals on Sunday as Rafael Nadal prepared to launch his bid for a first title at the elite eight-man event. In a repeat of last year's final at London's O2 Arena, won by Tsitsipas, US Open champion Thiem stumbled after winning a first-set tie-break but found his range again to win 7-6 (7/5), 4-6, 6-3.

Thiem was impressive on serve in the first set, winning 79 percent of service points, but failed to convert three break points against the Greek world number six. The Austrian third seed found himself in deep trouble when trailing 4-1 in the tie-break but battled back and made his first set point count when Tsitsipas went long with a backhand lob. Tsitsipas produced a forehand winner in the third game of the second set to break the Austrian and haul himself back into the contest, facing no break points as he levelled the match.