Team Europe are poised to seal yet more Laver Cup glory after producing another dominant display against Team World, though the focus was on Nick Kyrgios following comments about his long-term future.
Europe swept Saturday's four matches in Boston to stand on the cusp of a fourth consecutive Laver Cup triumph – the defending champions lead 11-1 and require just two more points to clinch the title.
Stefanos Tsitsipas blitzed Team World's Kyrgios 6-3 6-4 at TD Garden, where Olympic Games gold medallist Alexander Zverev beat John Isner 7-6 (7-5) 6-7 (6-8) 10-5 before US Open champion Daniil Medvedev made light work of Denis Shapovalov 6-4 6-0.
Team Europe secured their fourth win of the day in the doubles – Tsitsipas and Andrey Rublev teaming up to defeat Isner and Kyrgios 6-7 (8-10) 6-3 10-4.
After Kyrgios' straight-sets loss to Greece's Tsitsipas, the 26-year-old Australian star casted doubt over his tennis future.
"This is my probably my last Laver Cup," former world number 13 Kyrgios – an Australian Open and Wimbledon quarter-finalist – told reporters post-match. "I don't know how much longer I will be in tennis.
"This is my last event of the year. I will get my body right ahead of the Australian Open.
"My mum is not doing too well with her health. I'd like to go back and see her."
"As long as I'm on the court, I will try and give my best, but I'm not going to lie and say that I'm going to plan to play four or five more years on tour," Kyrgios said. "That's just not me."
Playing for the first time since earning his maiden grand slam trophy at the expense of record-chasing Novak Djokovic at Flushing Meadows, world number two Medvedev suffered no letdown against Shapovalov.
"I played unbelievably, especially [in] the second set," Russia's Medvedev said in his on-court interview. "I didn't know what to expect because after the US Open, I didn't play for a week and a half. Came here, practised as much as I could the past three days, so I didn't hit [that] many balls, but was surprisingly feeling well.
"I wanted to show that also today. [The] first [set] was not easy, the ball was not going as fast as I wanted [and] he was playing really good. And then I just couldn't miss a ball anymore. I'm really happy about [that]."