World number two Simona Halep survived a tough challenge from Ukrainian qualifier Kateryna Kozlova to win their third round match 7-6(3), 7-5 at the BNP Paribas Open in Indian Wells, California, on Sunday.
The Romanian finally put away the 114th ranked Kozlova with eight consecutive points in the second set, a backhand winner proving the decider just as it had in the first set.
The tournament lost 23-times Grand Slam winner Serena Williams, who retired against Garbine Muguruza with what organisers described as a viral illness. The Spaniard was ahead 6-3, 1-0 at the time.
Halep said her opponent had been tough to put away.
"It was difficult for me to close out those sets. When I was leading the match, she played without fear," she told reporters.
The victory advanced the French Open champion, who won Indian Wells in 2015, to the fourth round for the fifth time in six years.
The meeting was the first between the pair and featured big momentum swings.
After Kozlova claimed a 3-2 advantage in the first set, Halep won three consecutive games to go to set point at 5-3 on Kozlova`s serve.
With the former world number one`s groundstrokes failing her, Kozlova reeled off 11 of the next 12 points, breaking back for 5-5 with a forehand winner.
Halep finally won the set on her third opportunity with another trademark backhand down the line.
The Romanian took four successive games for a 5-2 lead in the second set, but Kozlova again rallied to even the match at 5-5 before Halep reeled off the eight straight points to seal the win.
Former Wimbledon and French Open champion Muguruza was happy with the way she had been playing against Williams before the American`s retirement.
"I think I played well," she said. "I`m going to take the positive side of that."
Sixth seed Elina Svitolina, looking for her first title of the year, beat Daria Gavrilova 7-5 6-4 to advance while world number seven Kiki Bertens reached the fourth round at Indian Wells for the first time after a 7-6(10) 6-4 win over Briton Johanna Konta.
Bertens will next meet Spain`s Muguruza.
“Konta today, she can play really aggressive, and I think with Muguruza it’s the same," she said. "So I have to serve well, go for my shots myself again where I can, and hopefully play a little better than today.”
China’s Qiang Wang and Australia`s Ashleigh Barty also advanced.