Sixth seed Ons Jabeur suffered a surprise first-round defeat by Magda Linette on the opening day of the French Open.

Jabeur was among the favourites for the title, having reached three clay-court finals in the build-up to Paris.

Former champion Garbine Muguruza also fell to the ever-dangerous Kaia Kanepi but Sloane Stephens advanced.

Linette will face either Britain's Harriet Dart or Martina Trevisan of Italy next.

Jabeur, 27, had won 17 clay-court matches in the weeks before the French Open and became the first African to win a WTA 1,000 event at the Madrid Open.

She is a player known for reacting well under pressure, but cut a frustrated figure as the match progressed.

The two traded breaks in the opening set and Linette faltered when serving at 5-3 down to hand Jabeur the opener.

The Pole left court for treatment on her right thigh, which was heavily strapped, and struggled with her movement at the back of the court.

However, Jabeur missed four break-point chances in the second set and looked the less confident of the two as Linette forced a decider.

A tough final set saw both players break, with Jabeur having to dig deep to save two break points at 4-3, but Linette kept the pressure on.

Serving to stay in the match, the Tunisian squandered a 40-0 lead and double-faulted to hand Linette match point.

Linette converted it and raised her arms in triumph as she notched the third top-10 win of her career.

Jabeur said afterwards she was not happy to open the tournament on Court Philippe Chatrier.

"I've got quite a peculiar relationship with this court, I like it and I don't like it at the same time," she said.

"Honestly, I wasn't happy to play on a Sunday at 11."

Another big name falls victim to Kanepi

Muguruza, the 2016 champion at Roland Garros and seeded 10th this time, continued her wayward start to the season with a 2-6 6-3 6-4 loss to Estonia's Kanepi.

Kanepi, 36, is known as a giant-killer at the Grand Slams, having most recently upset then world number two Aryna Sabalenka at the Australian Open.

It was her 10th top-10 win at a Grand Slam. She has won 19 matches against seeds in the first three rounds at majors.

Spain's Muguruza, 28, led by a set and a break before Kanepi fought back to ensure a second-round match against Brazil's Beatriz Haddad Maia.

Earlier, 2018 runner-up Stephens claimed her first victory since March as she fought back to beat German qualifier Jule Niemeier.

The American came through 5-7 6-4 6-2 to set up a meeting with 26th seed Sorana Cirstea of Romania.

Last year's semi-finalist Maria Sakkari came through a tough test to beat France's Clara Burel 6-2 6-3.

The Greek fourth seed composed herself well after a fan heckled loudly from the stands as she served for the match, causing a lengthy delay.

Elsewhere, Swiss 14th seed Belinda Bencic beat Hungarian Reka Luca Jani 6-1 6-1, while American 18-year-old Coco Gauff, seeded 18th, won 7-5 6-0 against Canadian qualifier Rebecca Marino.