CINCINNATI: Roger Federer crashed to a third-round defeat in a first-time meeting with Andrey Rublev, who posted a 6-3, 6-4 upset on Thursday at the ATP Cincinnati Masters.
The seven-time Cincinnati champion, who turned 38 last week, was unable to make an impression as he played only his second match since losing the Wimbledon final to Novak Djokovic.
Rublev, a 21-year-old Russian qualifier who missed months last season with injury, was shell-shocked at his win over the 20-time Grand Slam champion.
"It's an amazing feeling when you play such a legend as Roger," he said. "At least 99 percent of the crowd was supporting him.
"Today I was just trying to do my best. I told myself I need to play every point to the end. No matter what the situation, I kept fighting."
Federer went down to the world number 70 in barely an hour, losing for only the 10th time here after winning 47 matches.
The Swiss will now head into the US Open later this month with just two matches on hard courts under his belt.
Rublev earned his second top-five win in a month after beating Dominic Thiem in Hamburg on his way to the final.
Frenchman Richard Gasquet ousted Diego Schwartzman 7-6 (8/6), 6-3 while Japanese qualifier Yoshihito Nishioka reached his second quarter-final of the season by defeating Australia's Alex de Minaur 7-5, 6-4.
The 77th-ranked Nishioka, who shocked compatriot Kei Nishikori on Wednesday, will next face either France's Adrian Mannarino or Belgian 16th seed David Goffin for a place in the semi-finals.
Nishioka, 23, advanced in 82 minutes, never facing a break point while twice breaking the Australian's serve.
Women's top seed Ashleigh Barty held off Anett Kontaveit as the Estonian served for victory before the top seed scraped a 4-6, 7-5, 7-5 triumph into the WTA event quarter-finals.
The win keeps the Australian in the chase for a possible return to the WTA number one ranking, which she lost to Naomi Osaka on the eve of this US Open build-up event.
Barty needs to reach Sunday's final in order to regain the ranking summit.
"It was a little bit scrappy at times today but proud of the way we were able to fight and hang in there right until the end," said the reigning Roland Garros champion.
"Ultimately that was the most important part about today was to try to hang in there as best that I can, fight right until the end and try and make a match of it.
"Towards the end, I started to find a little bit more rhythm but certainly struggled early on. It was more about the fight today than the tennis."
Victory came a day after Barty defeated five-time Grand Slam winner Maria Sharapova in the second round.
Barty will play Friday against Maria Sakkari of Greece, a 6-7 (4/7), 6-4, 6-4 winner over ninth seed Aryna Sabalenka.