Simona Halep moved closer to regaining the world number one ranking by coming from a set down to beat Polona Hercog 5-7 7-6 (7-1) 6-2 at the Miami Open.
The 27-year-old world number three lost her place at the top of the women's game following Naomi Osaka's Australian Open victory in January.
But after Osaka's shock exit in the third round in Miami, Halep can return to the top if she takes the title.
She next faces Venus Williams, who swept past 14th seed Daria Kasatkina.
American seven-time Grand Slam champion Williams beat the 21-year-old Russian 6-3 6-1 in just under 75 minutes on Sunday to reach the fourth round.