BIRMINGHAM, UK - No.1 seed Naomi Osaka was quick to find her feet on grass at the Nature Valley Classic, dismissing Maria Sakkari 6-1, 4-6, 6-3 in one hour and 59 minutes.

The World No.1's prior two encounters with Sakkari both came at significant junctures in her career. In the fourth round of Indian Wells last year, Osaka won 6-1, 5-7, 6-1 en route to her maiden title (indeed, that set was the only one she conceded that fortnight) - and five months later, she would lose to the Greek player 6-3, 7-6(8) in the first round of Cincinnati, the last match before her thrilling run to her first Slam championship at the US Open.

Osaka has spoken self-deprecatingly this week about being "not really that comfortable" on grass, despite third-round showings on her first two appearances in the Wimbledon main draw - but there was no trace of this apprehension in a dominant 27-minute opening set.

After saving two break points in her first service game with some clutch serves, the Japanese player steamrolled to reel off six consecutive games for a hidden bagel.

Osaka proved equal to dealing with some of the more awkward bounces dealt by the grass court, repeatedly clattering powerful forehands past Sakkari with ease. Instead, it was the World No.33 who struggled to find her range - particularly on serve.

Five double faults, including three in a row to get broken for the first time in the third game of the match and another facing break point for the double break, made for something of a nightmare passage of play for Sakkari - and Osaka rubbing salt into the wound by hammering return winners when Sakkari eventually did get her serve in did not help.

The Rabat champion was able to rein those mistakes in during a high-quality second set, though. With both players emerging with a positive winner-unforced error differential, it was Sakkari who came through a mid-set exchange of breaks with the momentum - which she used to break again and sneak the set.

Having been dragged into a dogfight from a position of dominance, it took all of Osaka's reserves to wrest back control. The pivotal game of the deciding set was the fifth. The US Open and Australian Open champion valiantly staved off six break points - and once she had that tussle under her belt, began to roll again, immediately breaking Sakkari for 4-2.

Though Sakkari would force Osaka to serve for the match and take a 0-30 lead in that game, the World No.1's serve again came to the rescue as she reeled off the final four points to set up a second-round meeting with Yulia Putintseva.