Johanna Konta impressed in her first match since reaching the French Open semi-finals to ease into the second round of the Nature Valley Classic in Birmingham.

The British number one made a seamless transition from clay to grass, beating big-hitting Estonian Anett Kontaveit 6-4 6-2.

Kontaveit is only ranked two places lower than world number 18 Konta but the seventh seed played at a high level throughout and wrapped up victory in an hour and 12 minutes.

The only blip came when she dropped serve at 4-3 in the opening set but she reestablished her advantage straight away and the second set was particularly impressive, with Konta displaying her more rounded game to great effect.

There was disappointment, though, for British number two Heather Watson, who let a lead slip in a 3-6 6-3 6-4 defeat by Barbora Strycova.

Watson was unhappy with a number of line calls and declined to shake the umpire's hand at the end of the match.

Russia's Margarita Gasparyan pulled off an upset in the opening contest of the day, defeating fourth seed Elina Svitolina 6-3 3-6 6-4.

Svitolina had been struggling with a knee injury and, despite ending a four-match losing streak by reaching the third round of the French Open, she admitted she may be forced to skip the grass.

Happily that was not the case and the Ukrainian said: "I feel better, definitely. It hasn't been easy for the past three months I would say, mentally as well. So I'm just happy to be on court playing and without the pain."

Fifth seed Aryna Sabalenka also exited the tournament, showing her frustration as she lost a break advantage in the final set to go down 6-3 2-6 7-6 (1) to Hsieh Su-wei.

World number one Naomi Osaka will open her campaign on Tuesday with a tricky clash against Greek Maria Sakkari, and admitted her expectations are low in her first grass-court tournament of the season.

"I'm not really that comfortable with it," she said. "And it's always the first tournament that's the hardest. I have only practised twice on grass because it was raining a lot."

Osaka has yet to make it past the third round at Wimbledon, and she added: "Whenever I come to grass I can only remember the last match I played, which is always Wimbledon, and last year I played against (Angelique) Kerber and she kind of crushed me.

"So that is the thing that I remember the most. I'm going to try and think about that match but think about everything that I improved during the year."