Maria Sharapova survived a nearly three-hour match to beat Michaella Krajicek of the Netherlands 7-6 (4), 6-7 (3), 6-4 on her third match point on Thursday to reach the quarter-finals of the East West Bank Classic.
"Serving against the wind and playing against the wind with that sun, especially in the beginning, was pretty difficult," she said. "It definitely felt like a break-fest out there."
Sharapova, the top seed, beat Krajicek for the second time this year. The Russian struggled with her serve before eventually winning the final three games of the match.
"It's one of those days and you're just happy to get a W," she said.
"I felt like I was a little slow and didn't see the ball. I was a step late to everything," she said.
No. 2 seed Jelena Jankovic defeated 13th-seeded Sybille Bammer of Austria 6-2, 6-1 and will play Victoria Azarenka of Belarus on Friday.
"I'm waiting to be 100 percent so I can play without blowing my nose," said Jankovic, who has a nagging cold. "Being sick wears you down."
Sharapova committed forehand errors on her first two match points before she returned Krajicek's serve with a crosscourt backhand on the third.
"She was starting to serve really well. Some of those second serves that she had on match point were probably over 100mph [160kph]," Sharapova said.
The Russian is coming off a title in last week's tournament near San Diego. She will defend her US Open championship in two weeks.
"This is all the preparation that goes into a Grand Slam," she said. "You want to be able to take that confidence and bring it into the Open."
Defending champion Elena Dementieva advanced when No. 5 Daniela Hantuchova retired from their match down by a score of 6-3, 4-1 because of an upper respiratory illness.
Hantuchova fell victim to the same bug that forced Eleni Daniilidou to quit in the second set against Sharapova on Wednesday night. It has affected some of the other players, too.
"Once it starts to get around, it is very easy to get sick," Hantuchova said. "As soon as I had to hit more than two shots, I was dead. I have been taking everything but antibiotics."
Other winners on Thursday were No. 3 seed Ana Ivanovic, No. 4 Nadia Petrova, Maria Kirilenko and Virginie Razzano.