Italian top seed Jannik Sinner defeated American Taylor Fritz 6-4 6-4 to move closer to the last four of the ATP Tour Finals.
The 23-year-old world number one fought off stubborn resistance for his second win in front of a home crowd in Turin.
Sinner, who beat Fritz in September’s US Open final, hit 22 winners to Fritz’s 19 as he edged a compelling encounter.
Earlier, a rejuvenated Daniil Medvedev defeated Alex de Minaur 6-2 6-4 in the Ilie Nastase Group.
Fourth seed Medvedev was irate during his opening defeat by Fritz on Sunday but was far more settled in Tuesday’s victory.
Meanwhile, Britain’s Henry Patten and partner Harri Heliovaara are through to the doubles semi-finals after a second straight triumph.
Sinner, who also took the 2024 Australian Open, tops the group table with one round to go as he seeks another big tournament triumph in a year where he has also been embroiled in an ongoing doping controversy.
The winner of seven tour titles in 2024, he was claiming his 67th win from 73 matches – cheered on by a capacity crowd of 12,000 which included Italian football great Andrea Pirlo.
“It was a very tough match – we got to know each other very well in a Grand Slam final,” said Sinner.
“The crowd is helping me a lot, and it’s a big occasion for me.”
Fritz had earned the match’s first break point in the seventh game but could not make it count.
The American fifth seed fought back from 0-40 behind in the next to level at 4-4 before succumbing on his following service game as Sinner piled on the pressure to clinch the first set.
A similarly tight second set followed and again Sinner stepped up to shatter his opponent’s resolve, as typified by a breathtaking backhand down-the-line winner en route to going 4-3 ahead on serve.
He went on to gain the crucial break, courtesy of a Fritz double fault, for a hard-fought but deserved victory.
