Serena Williams beats sister Venus to reach last eight

Venus Williams of the U.S.A. wipes her face as Serena Williams of the U.S.A. looks on during their match at the Wimbledon Tennis Championships in London, July 6, 2015.[Photo/Agencies]

"I'm not really considering it like, 'Wow, a breakthrough,"' she said. "I had set goals of what I wanted to do, and because I'm achieving it doesn't mean it's a breakthrough."

Vandeweghe will next face fourth-seeded Maria Sharapova, the 2004 champion who downed Zarina Diyas of Kazakhstan 6-4, 6-4. Sharapova has not dropped a set so far, losing only 23 games in four matches.

The 20-year-old Keys got to the Wimbledon quarterfinals for the first time, beating 122nd-ranked Olga Govortsova of Belarus 3-6, 6-4, 6-1. Keys, who reached the semifinals at the Australian Open this year, has now beaten three players here who were ranked outside the top 100.

"I definitely feel like when I'm walking out onto the courts, not only do I feel people are expecting me to win but I am expecting me to win," Keys said.

In early men's play, Richard Gasquet held off 20-year-old Australian Nick Kyrgios 7-5, 6-1, 6-7 (7) 7-6 (6) to advance to the Wimbledon quarterfinals for the first time since making it to the semifinals in 2007.

Vasek Pospisil came from two sets down to overcome No. 22 Viktor Troicki 4-6, 6-7 (4), 6-4, 6-3, 6-3. Pospisil is the third Canadian man to reach the quarterfinals at Wimbledon, after Robert Powell (1908, '10, '12) and Milos Raonic (2014).