Germany's Alexander Zverev reacts after defeating Spain's Rafael Nadal during their first round match of the French Open tennis tournament at the Roland Garros stadium in Paris on Monday. AP

Rafael Nadal's illustrious French Open career came to a likely end with his first ever defeat in the opening round by Alexander Zverev on Monday, after Iga Swiatek made a winning start in her bid for a fourth title.

Nadal matched world number four Zverev for long periods on a packed Court Philippe Chatrier, but slipped to a 6-3, 7-6 (7/5), 6-3 loss as he was beaten for just the fourth time in 116 matches at the tournament.

This year's event was expected to be the 14-time champion's farewell to Roland Garros, but he had since insisted he could not confirm "100 per cent" it would be his last appearance.

"If it is (the last time), then you have been amazing," Nadal told an adoring crowd under the Chatrier roof.

"The feelings I have today are difficult to describe in words. It is the place I love the most."

Nadal, who turns 38 next week, showed all his trademark fighting qualities in a gripping match, but only managed to convert two of 11 break points against an inspired opponent.

"The first round wasn't ideal," he admitted, before saying he "hoped" to be back at Roland Garros later this summer for the Paris Olympics but would almost certainly skip Wimbledon.

"It will be difficult playing on grass considering that right after Wimbledon are the Olympic Games."

Rafael Nadal reacts as he plays against Alexander Zverev at the Roland Garros stadium in Paris, on Monday. AP

It was only Nadal's fifth tournament since January 2023 after suffering a hip injury and then a muscle tear, arriving in Paris a lowly 275th in the world rankings.

"It's hard to say about the future," he added. "I am travelling with my family and I am having fun. The body is feeling better than it did two months ago."

Nadal was unseeded for the draw and vulnerable to a difficult opening round.

German Zverev, who lifted the Rome Open title last month, proved too strong despite the fans desperately attempting to raise Nadal to past glories.

The 27-year-old banished the memories of the duo's last meeting, when he left Chatrier court on a wheelchair after injuring his ankle during their 2022 French Open semi-final.

His reward for becoming just the third player to defeat Nadal at Roland Garros -- after Novak Djokovic and Robin Soderling -- is a match against either David Goffin or home wildcard Giovanni Mpetshi Perricard.

Zverev's fast start

Zverev started the match strongly with a break to love in the opening game, going on to wrap up the first set with relative ease.

Rafael Nadal (right) checks hands with the winner Alexander Zverev at the Roland Garros Complex in Paris. AFP

Nadal was much improved from his most recent outing, when he was well beaten by Hubert Hurkacz in the Rome second round, but failed to serve out the second set when leading 5-4.

Zverev then came out on top in a tense tie-break as a Nadal return found the net.

The Spaniard again broke first in the third set to lead 2-0, much to the delight of the 15,000 spectators in attendance, including Djokovic, Carlos Alcaraz, Swiatek and Manchester City footballer Rodri.

But Zverev quickly hit back once more, before breaking for a 4-3 lead with a wonderful passing winner.

He secured victory on his first match point as Nadal blazed a forehand off target, potentially ending the most dominant career at a single event in Grand Slam history.

Agence France-Presse