Third seed Iga Swiatek reached the Cincinnati quarterfinals with a 6-4 6-4 win over Sorana Cirstea on Wednesday, while defending champion Jannik Sinner beat Adrian Mannarino following a lengthy rain delay.

Wimbledon champion Swiatek extended her perfect record against Cirstea to 5-0 and will next face the winner of an all-Russian clash between Anna Kalinskaya and Ekaterina Alexandrova.

"We played many tough matches, so I know Sorana can really hit the ball well, especially on faster surfaces," Poland's Swiatek said.

"I'm happy I was solid enough. I was trying to be proactive with my serve, not many of my first serves went in, but I was happy I was solid on my second serves."

Fellow Pole Magda Linette upset fourth seed Jessica Pegula 7-6(5) 3-6 6-3 in a third-round match that extended over two days after Tuesday's suspension due to rain.

The American had levelled the match at a set apiece, but on Wednesday's resumption Linette earned the break before closing it out on serve for her second Top-10 win of the season.

In the men's draw, top seed Sinner kept his title defense on track, beating French qualifier Mannarino 6-4 7-6(4) after an almost three-hour rain interruption.

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The Italian struggled to find his rhythm, failing to serve out at 6-5 but sealing the tiebreak with back-to-back aces for his 24th consecutive hard-court victory.

Mannarino "is a very tough opponent. Very different from other opponents, not only because he is a lefty but how he hits the ball. It is very low," the 23-year-old Sinner said. "I just tried to serve well and tried to see what I could do in the return games".

Sinner will face either 23rd seed Felix Auger-Aliassime or France's Benjamin Bonzi in what will be his fifth quarterfinal this year.

Ben Shelton, whose match was also halted after the first set, advanced to the round of 16 with a 7-6(3) 6-3 win over Roberto Bautista Agut. The American fifth seed will next face Czech Jiri Lehecka.

Alexander Zverev completed a 6-4 6-4 win over Brandon Nakashima after the match was suspended overnight when he was leading 5-4 in the second set.

The German third seed is set to return to the court later on Wednesday, aiming to avenge last week's Toronto semifinal loss to Russian Karen Khachanov.

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Earlier, seventh seed Holger Rune advanced after home favorite Frances Tiafoe was forced to retire with a back injury.