PARIS - World Number 1 Novak Djokovic dominated his first round match at the French Open on Tuesday, sweeping aside Sweden's Mikael Ymer 6-0, 6-2, 6-3 in just 98 minutes.

The Serb frequently used drop shots throughout the game, just as he did during his Rome title run last week.

"I think it's a great variety shot, the dropshot. I think it's important tactically to have it and to use it at the right time so that you can keep your opponent always guessing what the next shot is," said the top seed, who is seeking his 18th Grand Slam title at Paris.

"I may have played too many today. I agree. Maybe I exceeded what I should have played. But I think it worked well in the moments when I needed to get the point I did."

With the victory over Ymer, Djokovic improved his record this season to a stellar 32-1. The only defeat came in a disqualification earlier this month at the US Open, where he hit a ball in frustration which struck the line judge on the neck.

The 2016 French Open winner said at a press conference on his arrival in Paris that he would "make sure not to make the mistake twice."

Local favourite Kristina Mladenovic was a victim of a missed call in her first round defeat to Laura Siegemund of Germany on Tuesday.

She should have won the first set when she was up 5-1 and had a set point, which TV replay showed she had converted it with a dropshot as Siegemund failed to return it before it had bounced twice. But the umpire Eva Asderaki did not rule the point in Mladenovic's favor.

"I think the chair umpire was the only person not to have seen it," said a furious and disappointed Mladenovic after the match.

"Mistakes are human, but I don't see how the umpire can miss that. She didn't see a double bounce," the 2017 French Open quarterfinalist added.

After squandering seven set points, Mladenovic was unable to close out the set, losing 7-5 before losing the second set 6-3.

Earlier in the day, Czech Karolina Pliskova survived a scare from Egyptian qualifier Mayar Sherif after she came back from one set down to beat her opponent 6-7(9), 6-2, 6-4 to reach the second round.

The former world No. 1 is set to face a tougher challenge in the second round against 2017 champion Jelena Ostapenko of Latvia, who knocked out American Madison Brengle 6-2, 6-1.

Pliskova wasted eight set points in the opener but recovered quickly in the following two sets, serving out the contest on Court Philippe-Chatrier after two hours and 15 minutes.

The 24-year-old Sherif, who ranks 172 in the world, was the first Egyptian woman to appear in a Grand Slam main draw, while Pliskova, 27, is bidding for her first major title in her 33rd Grand Slam appearance.

Also on Tuesday, men's seventh seed Matteo Berrettini of Italy cruised to a 6-3, 6-1, 6-3 victory over Canadian Vasek Pospisi.

Greece's fifth seed Stefanos Tsitsipas had to dig deep to outlast Jaume Munar 4-6, 2-6, 6-1, 6-4, 6-4 after three hours and 12 minutes to advance, while Andrey Rublev of Russia also recovered from two sets down to dispatch American Sam Querrey 6-7(5), 6-7(4), 7-5, 6-4, 6-3 to claim the first-round win.