Serbia's Novak Djokovic congratulates Austria's Dominic Thiem. Photo: Petr David Josek/AP

US tennis legend John McEnroe accused Novak Djokovic of giving up in his stunning French Open exit at the hands of Dominic Thiem on Wednesday.

Defending champion Djokovic collapsed to a meek 7-6 (7/5), 6-3, 6-0 loss to Thiem in what was his earliest exit at Roland Garros in seven years.

Defeat also meant that just 12 months after holding all four Grand Slam titles, the 30-year-old was left fighting to prove he is still a relevant force in the sport.

"I don't remember seeing a time in the last six to eight years when Novak mailed it in," seven-time major winner McEnroe told the BBC.

"He basically gave up."

Wednesday's loss was just the ninth time that Djokovic had suffered a 6-0 'bagel' set and first at a Slam since facing France's Gael Monfils at the US Open in 2005 when he was still a teenager.

"It looked in the third set like he just didn't want to be out there, couldn't compete any more, and that's shocking for a guy that's won as much as he has and prides himself on competition," added McEnroe.

"It just shows you everyone's human."

McEnroe added: "If you had told me a year ago, when he was the only guy since Rod Laver holding all four Slams that this is what we'd be talking about now, I'd have told you you were nuts."