MASON, Ohio — Rafael Nadal and Karolina Pliskova — the No. 1 seeds in the Western & Southern Open — advanced with straight-set wins on a day when other top players weren't so fortunate.

Nadal beat Richard Gasquet 6-3, 6-4 on Wednesday night. Defending-champion Pliskova needed only 67 minutes to get a 6-2, 6-3 win over Natalia Vikhlyantseva.

The rest of the day was highlighted by upsets.

Venus Williams' resurgent summer hit a bump when she was knocked out by a qualifier in the second round.

No. 3 Angelique Kerber lost to Ekaterina Makarova 6-4, 1-6, 7-6 (11), with the Russian converting on her eighth match point.

On the men's side, wild card Frances Tiafoe broke through against No. 4 Alexander Zverev, who was coming off his second ATP Masters title in Montreal.