BIRMINGHAM, Great Britain - Daria Gavrilova triumphed in an all-unseeded first-round battle of former Top 20 players on the first day of the Nature Valley Classic, making her way past Dominika Cibulkova 6-3, 7-6(6) in one hour and 45 minutes.

Though the pair's head-to-head was all square at 1-1, it was the Slovak who had the grass-court advantage coming into today's match. An Eastbourne champion and Wimbledon quarterfinalist in 2016, Cibulkova had in fact beaten Gavrilova 6-3, 6-2 in the second round of the latter tournament. By contrast, the Australian's career main draw record on the surface before today was a mere 8-10.

Still, Gavrilova is coming round to grass these days, despite acknowledging that clay remains her favorite surface. "I actually enjoy playing on grass," she revealed afterwards. "The points are much quicker, and I think I've got the weapons to make some damage."

The World No.25 had evidently found her feet on the Birmingham lawns with little trouble. Moving smoothly and hitting cleanly, Gavrilova also proved adept at exploiting the nuances of the surface. The 24-year-old varied the spins and paces of her shots and made excellent use of a deep, biting slice both to take the sting out of her opponent's relentless attack and to disrupt Cibulkova's rhythm.

A tightly contested opening set ended with barely a difference between the two players statistically, each tallying six winners and 15 unforced errors. Indeed, it was the 2014 Australian Open runner-up who was proving more reliable on serve, landing 79% of her first deliveries to Gavrilova's 67%.

Crucially, though, the Sydney and Acapulco semifinalist proved more clutch on the biggest points. Having garnered an early breakthrough, Gavrilova would effectively protect her own serve for the remainder of the set - facing just one break point, and saving it with an ace - before a flurry of backhand errors from Cibulkova sealed a double break and the set.

As the match drew on, the 2016 WTA Finals champion began to find her own range, frequently pulling off her trademark high-risk baseline winners as the second set settled into a rhythm of comfortable holds. Neither player would face a break point until the seventh game, when Cibulkova upped the pace on her forehand side - and snatched her first opportunity with a crosscourt winner.

However, one of the most significant aspects of Gavrilova's performance today was her calmness under pressure. "I kept my cool - it doesn't happen too often!" she joked afterwards. Unfazed, she immediately turned the tables, withstanding a barrage of Cibulkova rockets to nail a pass and subsequently go on to retrieve the deficit.

Similarly, Gavrilova did not lament the passing of three match points with unforced errors in the 11th game of the set - but instead approached the ensuing tiebreak with positive play, serving solidly and turning defence into offence with patient point construction. A strange, shanked forehand slice at 4-3 seemed to tilt the momentum back towards Cibulkova, who carved out two set point chances - but a double fault wasted the first, before Gavrilova triumphed in one of the best rallies of the day with an instinctive, sudden dropshot winner.

One point later, it was the former World No.5 who threw in a surprise dropshot - but Gavrilova was equal to it, chasing the ball down for a brilliant get. Another forehand error from Cibulkova concluded a compelling contest, and a fine reward for Gavrilova's cool head.

"I just thought I had to keep fighting," explained the 2017 New Haven champion, who next faces eithe rNo.4 seed Petra Kvitova or Johanna Konta. "I was not overly happy when she had set points, and I got a bit lucky when she double faulted - but I'll claim it because I felt I was making enough pressure for her to shake!"