Johanna Konta's competitive instincts helped her overcome a second-set wobble in her opening-round clash against Lesia Tsurenko at the Aegon Classic in Birmingham.
The British No.1 had little time to adjust to the courts at the Edgbaston Priory Club after reaching the final of the Nottingham Open on Sunday.
There she suffered a shock loss to Donna Vekic, and the world No.7 was in trouble again when she trailed 5-2 against Ukraine's Tsurenko in the second set.
But Konta won three games in a row and then took her third match point in the tie-break to win 6-3, 7-6 (8/6).
She said: "I felt actually throughout the whole match maybe I just dropped my level a little bit. In that one service game, when she broke me and she gained momentum back and started playing better.
"It was actually really tough to hold on. But I felt I stayed in each point quite well. I competed well in each of them, and I really just tried to do the best that I could."
The 27-year-old called for the doctor early in the second set. She did not want to reveal the problem after the match but insisted: "Everything is fine."
In the second round Konta will face big-serving American Coco Vandeweghe, who defeated countrywoman Christina McHale 6-4 6-2.
The pair have not met before on the WTA Tour but Konta knows she is in for another tough battle, with Vandeweghe having reached the quarter-finals of Wimbledon two years ago and the fourth round last year.
"She's a very big player," Konta said. "She's got a lot of fire power, a lot of weapons. And I know she enjoys the grass."
Earlier, Petra Kvitova marked her return to her beloved grass with a 6-2 6-3 victory over fellow Czech Tereza Smitkova.
The two-time Wimbledon champion took a wild card into the tournament after making a quicker-than-expected recovery from the serious hand injuries she suffered when she was stabbed by an intruder exactly six months ago.
Kvitova made her comeback at the French Open, partly so she could focus solely on tennis when the grass season came around.
"It feels different," she said. "I'm happy that I have everything done with the media and the pressure and everything with the comeback in Paris.
"So I'm glad that now I can focus on tennis, especially on the grass. And that's important that I am back in reality and just playing the matches."
Kvitova, who next meets Britain's Naomi Broady, was content with both her performance and the condition of her hand.
The 27-year-old suffered wounds to all five fingers, with nerve damage in two of them, and is still treading carefully.
She said: "I think this first match on the grass was pretty good. I think that I served well and I played good shots from the baseline.
"I think that she served very well, especially first serve. I had good timing on the court today and I'm happy with the way I played.
"We are still worried about the hand, so we are not practising that much. We still have days off to work on my hand, and it was very good today. So I'm happy with that the most."
Fifth seed Kristina Mladenovic began her campaign with a 6-3, 7-6 (7/2) victory over Duan Ying-Ying.
Third seed Dominika Cibulkova was upset in a lengthy clash against Czech Lucie Safarova, losing 5-7, 7-6 (9/7), 7-5 having twice held match point in the second-set tie-break.
Sixth seed Garbine Muguruza was also tested by qualifier Elizaveta Kulichkova but came through 6-3, 3-6, 6-4.
Nottingham champion Donna Vekic was not able to continue her winning run, losing 6-2, 7-6 (7/2) to American Alison Riske.
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