INDIAN WELLS, California - Venus Williams defeated Anastasija Sevastova of Latvia 7-6 (8), 6-4 to reach the quarterfinals of the BNP Paribas Open on Tuesday as the oldest woman in the draw.

The 37-year-old American was coming off a straight-sets victory over sister Serena a night earlier, ending a three-match skid against her younger sibling.

"It was a quick turnaround from last night when it feels like, 'Hey, you're only in the fourth round,'" Williams said on court.

Playing under cloudy skies in intense heat, Williams had her hands full with the 27-year-old Sevastova, using drop shots, top spin and lobs to jerk her opponent side to side.

"There were some points where she just played and it was too good," Williams said.

"I thought I was in control of the point and winning the point, and she turned it around. It's just real talent."

After early losses in her first two tournaments of the year, Williams hasn't dropped a set at Indian Wells, where she has yet to reach the final in six previous appearances.

Awaiting Williams in the quarterfinals is 27th-seeded Carla Suarez Navarro of Spain, who beat American wild card Danielle Collins 6-2, 6-4.

Meanwhile, world No 1 Simona Halep is on track to retain her ranking after defeating Wang Qiang of China 7-5, 6-1 in the fourth round.

Halep is the only former Indian Wells winner left in the women's draw after No 20 Daria Kasatkina upset No 2 Caroline Wozniacki 6-4, 7-5.

Wozniacki blew a 3-0 lead in the first set and was on the run most of the match before losing for the second time this year to the 20-year-old Russian.

Halep improved to 17-1 this year and needs only to reach the final to stay at the top.

Halep watched Venus Williams' victory over 36-year-old sister and new mother Serena on Monday night.

"I love the way that they are motivated and they are still playing at this age, Serena with the kid," Halep said.

"It's a great thing what they do for sport, and it's great that tennis has them.

"I have many things to learn from them. That's why I'm trying just to go in to watch every time I can."

Associated Press