Garbine Muguruza has begun her reign as No.1 with a 6-4 6-0 win over Monica Puig, earning a spot in the quarter-finals of the Pan Pacific Open.

Playing in her first tournament since earning the WTA’s top ranking, the Wimbledon champion broke The Puerto Rican on Wednesday to go up 5-0 in the second set and then won with her third ace of the match.

Puig beat Muguruza 6-1 6-1 at the Rio Olympic Games and maintained that momentum early, but the Spaniard found her pace by breaking in the opening game of the second set. Another break came during a run of 12-straight points as she raced out to a 4-0 lead.

Muguruza will next face Kurumi Nara or Caroline Garcia as she contests the last eight for the fourth-straight year.

Muguruza took over at No.1 from Karolina Pliskova, who also advanced with a 6-2 6-1 win over Magda Linette.

After coasting through the first set, the Czech broke her opponent with a backhand into the corner in the sixth game before serving out to win.

The second-seeded Pliskova, who had eight aces against Linette, will face seventh-seeded Angelique Kerber or Daria Kasatkina in the quarter-finals.

Also, Anastasia Pavlyuchenkova of Russia advanced with a 6-4 4-6 6-2 win over Wang Qiang.