Diego Schwartzman battled back from behind to defeat Stefanos Tsitsipas and secure victory for Argentina over Greece in the ATP Cup.
Tsitsipas, 23, was playing in his first singles match since elbow surgery in 2021.
He won the first set, but Schwartzman, 29, rallied before sealing a fine 6-7 (5-7) 6-3 6-3 comeback win.
Earlier, Argentina's Federico Delbonis beat Greece's Michail Pervolarakis 7-6 (7-5) 6-1.
Speaking after beating Tsitsipas, world number 13 Schwartzman said: "I was just trying to think that it was his first match for two months after his elbow [injury], so I was thinking just to try and be in the match.