Vandeweghe came into this event with pleasant memories of California, as she made her WTA debut at San Diego in 2006, recorded her first WTA win at Los Angeles in 2009, scored her lone Top 10 win over Vera Zvonareva at Carlsbad in 2010 and made her first WTA final here in Stanford as a lucky loser in 2012. Her 2014 grass court season was highlighted by her first WTA title at 's-Hertogenbosch.
First-time Stanford competitor Kerber was kicking off her North American hardcourt swing after a strong grass court season that saw her reach the final at Eastbourne and the quarterfinals at Wimbledon, where she beat Maria Sharapova in the fourth round.
The Turning Point
Kerber pulled out a tightly contested first set, but then did not even muster a game in the second set. However, with Vandeweghe serving up 40-0 in the first game of the third set, Kerber won five straight points to seize an early break and the momentum. She eventually got up 4-0 and went on to a 7-6(4), 0-6, 6-2 triumph.
By The Numbers
Vandeweghe had the advantage in most of the statistics. She won eight more points than she lost, broke serve four times compared to three for Kerber and had 13 aces compared to 0. But that all-important first service game of the third set proved to be the American's downfall.
"The first set was very tough and very close, and I pulled it out in a tie-break," Kerber said. "In the second set, I completely lost my rhythm, but I got it back in the third set. It was a tough opener for me, but I'm happy to be in the quarterfinals."
"I played very well the whole match," Muguruza said. "I've been practicing and playing a lot, so I knew before I came here that my game was in good shape for Stanford."