Elina Svitolina, who came within two wins of becoming world No.1 in January, has maintained her ambitious momentum to reach the top by surviving a tricky start to her Wimbledon build-up at the Birmingham Classic.
The second-seeded Svitolina stumbled within sight of a two-set victory and briefly faltered again in the last set before beating Donna Vekic of Croatia 6-1 3-6 6-1.
Svitolina showed glimpses of the tenacious movement and consistently ferocious drives which have earned her the best win-loss record on the WTA tour since the beginning of last year, but also revealed glimpses of insecurity on the lush, low-bouncing surface.
Despite leading by a set and a break, her gradually increasing attempts to win points in the forecourt were of variable quality, while Vekic, a former runner-up in Birmingham, began to contain and counterattack more effectively.
Svitolina nearly let slip another lead of 3-1, in the last set, needing to save two break points on her next service game.
Eventually, the Ukrainian's determination to adapt tactically to a surface on which she has yet to progress beyond any quarter-final paid timely dividends, and she accelerated toward the finish line.
"I was just trying to play well and to dominate, but she played a couple of great points to break back - which is always nice to have," said Svitolina, apparently pleased to gain extra practice on a testing surface.
"It was difficult for me because she hit the ball very flat and the first match on grass is always a challenge."
She next faces Alize Cornet of France, who who outlasted former top-10 player Ekaterina Makarova of Russia, by 5-7 6-4 6-1.