Dominic Thiem proves too good for Cilic

French Open

* Serena digs deep to find a way past Ahn

* Kvitova sails into second round

* Bertens sets up second-round clash with Errani

PARIS: Dominic Thiem showed no sign of a hangover from his US Open triumph as he began his Roland Garros campaign with an impressive 6-4, 6-3, 6-3 win over Marin Cilic on Monday.

Third seed Thiem, beaten by Rafael Nadal in the last two French Open finals, was handed a tough first round against the Croatian former US Open champion, but was straight into the groove under the roof on Court Phillipe Chatrier.

Cilic, who before Thiem's Flushing Meadows win this month was the most recent first-time Grand Slam champion courtesy of his New York title in 2014, made things difficult for Thiem with some aggressive tactics but faltered at crucial moments.

Thiem broke the Cilic serve at 4-4 in the first set and then came from 0-40 down to seal the opening set.

Using his powerful single-handed backhand to damaging effect on the heavy claycourt, Thiem dominated the second set.

The 27-year-old lapsed briefly to trail 0-2 in the third but switched on the afterburners to reel off five games in a row before 40th-ranked Cilic stopped the rot.

Thiem had to save a break point when he served at 5-3 and claimed his fourth win in four meetings with Cilic as the Croat netted a return off a second serve.

Sixth seed Serena Williams battled sluggish conditions to defeat fellow-American Kristie Ahn 7-6(2), 6-0 to open her campaign.

Playing against an opponent she defeated at the same stage at the US Open less than a month ago, Williams found herself trailing twice in the opening set at the Court Philippe Chatrier but rallied each time to force a tiebreaker.

Williams, who has won three of her 23 Grand Slam singles titles at Roland Garros, raised her level in the tiebreaker and did not look back from there, handing the 102nd-ranked Ahn a bagel in the second set.

The 39-year-old had to dig deep to find a way to win points in the cold and heavy conditions and needed five match points to seal the victory and set up a second round meeting against Tsvetana Pironkova, who earlier beat Andrea Petkovic 6-3, 6-3.

Czech seventh seed Petra Kvitova put in a power-packed show to beat Oceane Dodin 6-3, 7-5. The 30-year-old twice Wimbledon champion lost only two points on serve in the opening set in her first clash with the French player, who has not got past the first round of a Grand Slam event since 2017.

Donin found her feet under the closed roof of Court Philippe Chatrier in the second set, which saw an early trade of service breaks, but Kvitova raised her game to get the break in the 11th game and close in on victory.

The Czech, who missed last year's tournament at Roland Garros due to an arm injury, sealed victory with a forehand volley for her 30th winner and will next play either Italian Jasmine Paolini, who beat Aliona Bolsova of Spain 6-4, 6-3.

Fifth seed Kiki Bertens recovered from a poor start against French Open debutant Katarina Zavatska to reach the second round with a 2-6, 6-2, 6-0 victory.

Dutchwoman Bertens was all at sea in the first set as the 20-year-old Zavatska took advantage of her errors.

Ukraine's Zavatska needed eight set points to seal the opener but clay-court specialist Bertens, a semi-finalist here in 2016, began to shake off the rust to take the second set.

Zavatska faded in the third set and was unfortunate as she broke racket strings three times in the space of two games midway through the second set.

Bertens, who sat out the US Open and retired with an Achilles injury on her return in Strasbourg last week, took full advantage and raced through the deciding set in 31 minutes.

She will play former runner-up Sara Errani in the next round after the Italian qualifier thrashed Olympic champion Monica Puig 6-2, 6-1 in her first Grand Slam match for two years.

In other first round matches, Third seed Elina Svitolina beat Varvara Grecheva 7-6, 6-4, Zhang Shuai beat Madison Keys 6-3, 7-6, Renata Zarazua beat Elsa Jacquemot 6-1, 6-2, Iga Swiatek beat 15th seed Marketa Vondrousova 6-1, 6-2, Hsieh Su-wei beat Barbara Haas 6-3, 7-6.

In men's section, Jiri Vesely beat Liam Broady 6-2, 5-7, 6-3, 6-2, Casper Ruud beat Yuichi Sugita 6-1, 6-3, 6-1, Lorenzo Sonego beat Emilio Gomez 6-7, 6-3, 6-1, 6-7, 6-3, Jack Sock beat Reilly Opelka 6-4, 6-4, 6-3. Agencies

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