BEIJING — Peng Shuai produced the upset of the first round in the China Open on Monday, beating sixth-seeded Venus Williams 7-5, 6-1.

The 30-year-old Chinese wild-card entry broke Williams’ serve twice in the second set.

In other matches, top-ranked Angelique Kerber defeated Katerina Siniakova 6-4, 6-4, No. 16 Elina Svitolina beat Tatjana Maria 6-2, 6-2, Daria Gavrilova beat Christina McHale 6-4, 6-4, and fifth-seeded Karolina Pliskova eliminated Lucie Safarova 6-7 (7), 6-1, 6-4.

Defending champion Garbine Muguruza, the French Open champion who is seeded second, beat Yulia Putintseva 6-2, 7-6 (5) in the second round.

“I’m very happy I could close the match in the tiebreak because obviously it was getting tougher and tougher,” Muguruza said. “Tiebreaks are moments where it’s delicate. You feel a bit more nervous and more tense.”

In the men’s first round, fifth-seeded David Ferrer beat Pablo Cuevas 6-4, 7-6 (3) and No. 7 Roberto Bautista Agut defeated Australian qualifier John Millman 6-4, 3-6, 6-3.