LYON, France - In the penultimate first-round match to be completed at the Open 6ème Sens - Métropole de Lyon, No.1 seed Sofia Kenin got her campaign up and running with a 6-4, 6-3 defeat of Vitalia Diatchenko in one hour and 24 minutes.

The American's first WTA Tour match win since lifting her maiden Grand Slam trophy at the Australian Open in January also exacted a measure of revenge on Diatchenko, who had been a 6-4, 6-1 victor in their only previous meeting, in the second round of Wimbledon 2018. Diatchenko had also defeated Maria Sharapova at that tournament en route to a career-best major third-round showing - but the Russian is yet to win a WTA main draw match since then, with today's loss marking her 10th consecutive first-round exit at this level. In a mark of Kenin's exponential improvement over the past two years, the 21-year-old was able to hold off Diatchenko's unpredictable and intermittently dangerous flat power to overturn the previous outcome.

Kenin had followed her Australian Open triumph with a win over Anastasija Sevastova in Fed Cup Qualifier action - but since then had lost three matches in a row, to Jelena Ostapenko in Fed Cup reverse singles, Elena Rybakina in Dubai and Dayana Yastremska in Doha. "

I didn't have the best two weeks," she acknowledged today. "But I had some tough opponents on a streak of playing some hot tennis and I was close, so it wasn't like I lost to someone who was no good.

"I'm just happy to have gotten the win. I'm happy, I played a really good match - she's such a tough player, so I'm really proud of myself - it's a good way to kick things off."

The low-key vibe of the inaugural Lyon tournament was also hitting the spot for Kenin, who said she had eaten "maybe the best food I've had in my life" at a local restaurant. "It's really chill, it's not so crazy - which I think I need right now," she said.

Kenin would assert her authority from the outset, spreading the ball around the court with well-placed forehands that had Diatchenko on the move, landing 78% of her first serves and mixing her play up with judicious dropshots. By contrast, the World No.107 was slower to get going: a double fault conceded her opening service game, and her backhand repeatedly found the net to fall behind a second break.

Up 5-1 in 21 minutes and seemingly cruising, Kenin suddenly found herself embroiled in a more complicated passage of play. Loosened up at last, Diatchenko began hitting her spots with her flat, double-fisted groundstrokes and began mounting a comeback.

Breaking Kenin as the World No.5 served for the set with a wickedly sidespun dropshot, Diatchenko rattled off three games on the trot, even surviving an ill-timed flurry of three double faults and two set points in the ninth game.

Though Kenin was able to halt her opponent's momentum to successfully serve the opening act out at the second time of asking, the Australian Open champion was relieved to land the final stab volley on her third set point.

Diatchenko's sterling resistance continued in the second set - but ultimately, it was Kenin's ability to sharpen her focus when she needed to that proved crucial, particularly compared to an opponent who seemed to alternate between double faults and aces, and fizzing winners and cheap errors.

It took Kenin six break points to capture the Diatchenko serve for a first time, and three more for a second - and in between, she would concede her own.

But emerging from this three-break sequence with the lead was key - as was a mid-set tussle on Kenin's own serve in which, having been 40-0 up, a series of unforced errors forced her to save two break-back points before holding with a marvellous redirected backhand winner down the line.

Another break of the Diatchenko serve swiftly followed as the 29-year-old coughed up another brace of double faults to take her final tally to nine - but as in the first set, Kenin was unable to close it out on her first chance as a ferocious backhand return winner sealed a break back to love for Diatchenko.

But throughout the match, the former World No.71's inconsistency had been her undoing, and once again she was unable to sustain this burst of form.

Kenin retained her focus despite the disappointment, getting her returns deep at Diatchenko's feet and reaping the rewards when, on her second match point, the Russian ricocheted a forehand into the bottom of the net.

Next up for Kenin in the second round will be surging Romanian qualifier Jaqueline Cristian, who sealed her first Top 50 win over Veronika Kudermetova in Fed Cup Qualifier action a month ago - and since then has posted a 10-1 win-loss record, including a 6-2, 6-0 demolition of Priscilla Hon in the first round this week.

2020 Lyon Highlights: Kenin dispatches Diatchenko