STANFORD, Calif. (AP) Reigning Wimbledon champion Garbine Muguruza eased by American Kayla Day 6-2, 6-0 to reach the quarterfinals of the Bank of the West Classic on Wednesday.
Muguruza, the top seed and fourth-ranked Spaniard, overwhelmed the 17-year-old in under an hour.
''Kayla has just won the US Open in juniors and she's just very promising, so I knew I had to be concentrated today,'' Muguruza said after her first match since Wimbledon.
Muguruza will play No. 5 seed Ana Konjuh, a 7-5, 6-5 winner over Russia's Natalia Vikhlyantseva.
Five-time major champion Maria Sharapova was scheduled to play, but withdrew with soreness in her left arm. Seventh-seeded Lesia Tsurenko moved on to face Madison Keys.
The third-seeded Keys rallied past qualifier Caroline Dolehide 3-6, 6-2, 6-3 in an all-American match. Keys won four straight games in the second set and made an early break in the third.