World number one Jannik Sinner reached the Cincinnati Open quarter-finals with a 6-4 7-6 (7-4) victory over a stubborn Adrian Mannarino.
Sinner quickly took control of the match when he broke the 37-year-old Frenchman in the third game.
Mannarino, ranked 89th in the world, saved a break point in the seventh game with an ace but the left-hander could not stop his opponent going on to claim the first set.
Play was suspended for rain with Sinner 40-30 on serve and 2-1 down in the second set, before the players resumed about two hours and 45 minutes later.
Mannarino proved a more obdurate competitor in the second set but, despite saving three break points at 5-5, eventually succumbed to the fourth when he netted a backhand to go 6-5 down.
Sinner was 30-0 up when serving for the match but some inspired tennis earned Mannarino his first break point which he took with a stunning forehand return.
However, Sinner produced back-to-back aces to win the tie-break 7-4 and extend his record to four wins in as many matches against Mannarino.
“He’s a tough opponent,” said Sinner. “Very different to all the other opponents. Not only because he is a leftie but also how he hits the ball – it’s very low.
“I struggled a bit to close it out but this can happen in this sport and I’m very happy to be in the next round.”
Elsewhere, Alexander Zverev needed just one game to complete his victory over Brandon Nakashima after rain had forced their match to be suspended overnight with the score 5-4 in the second set.
Zverev progressed 6-4 6-4, and will play again on Wednesday when he takes on Russian Karen Khachanov in the fourth round.
Meanwhile seventh seed Holger Rune is through to the quarter-finals after his opponent, American 10th seed Frances Tiafoe, retired with a back injury while trailing 6-4 3-1.
In the women’s draw, Wimbledon champion Iga Swiatek made it through to the last eight with a 6-4 6-3 win against Sorana Cirstea.
World number three Swiatek, of Poland, hit 33 unforced errors against the Romanian but managed to complete her match before the rain delay.
“I wanted to be more solid than in my last match,” Swiatek said. “I’m happy with the level of my focus and the consistency.
“It was a good match for sure. Not easy conditions as well – super humid – so I’m happy that I didn’t let this affect me.”
After their contest was suspended on Tuesday, fellow Pole Magda Linette completed a 7-6 (7-5) 3-6 6-3 upset against American fourth seed Jessica Pegula.
