Rafael Nadal won a 14th French Open and record-extending 22nd Grand Slam title on Sunday to become the oldest male champion at Roland Garros and then revealed he will undergo more treatment to cure a potentially career-ending foot injury.

In a disappointing final, 36-year-old Nadal routed Casper Ruud 6-3, 6-3, 6-0 with victory coming 17 years to the day since he claimed his first French Open as a 19-year-old in 2005.

Nadal won the last 11 games of the final and is now two Slams ahead of old rivals Novak Djokovic and Roger Federer with Sunday's victory coming against all the odds.

Nadal, the oldest winner in Paris since a 34-year-old Andre Gimeno in 1972, had not been certain of taking part after a chronic left foot injury, which has plagued him throughout his career, flared up again.

He also needed the best part of a gruelling 12 hours to see off Felix Auger-Aliassime, Djokovic and Alexander Zverev in the previous three rounds.

Victory: Rafael Nadal celebrates
Victory: Rafael Nadal celebrates AFP / Anne-Christine POUJOULAT

"It's obvious that with the circumstances that I am playing, I can't and I don't want to keep going. I'm going to keep working to try to find a solution and an improvement for what's happening in the foot," said Nadal.

He revealed he needed pain-killing injections in his left foot before every match in Paris and will undergo treatment again this week back in Spain.

"If it works, I keep going. If not, it will be another story and I will ask myself if I am ready to do a major surgery which may not guarantee I will be competitive and may take a long time to be back."

Nadal said that taking anaesthetic injections in the nerves in his foot was the only way he could have got through the tournament.

Now he and his medical team will employ a technique which will burn the nerve using what he described as "radio frequency injections" to "sleep the two nerves".

If it works, he said he intends to play Wimbledon where he is a two-time champion and which gets underway in three weeks' time.

Too good: Rafael Nadal celebrates
Too good: Rafael Nadal celebrates AFP / Thomas SAMSON

Nadal's two-hour 18-minute romp on Sunday took his record at the tournament to 112 wins against just three losses and also put him halfway to a calendar men's Grand Slam last achieved by Rod Laver in 1969.

"The most important thing is to congratulate Rafa," said Ruud.

"You are a true champion. This is the first time I have faced you so now I know what it's like to be the victim! There will be many others.

Trophy moment: Rafael Nadal celebrates
Trophy moment: Rafael Nadal celebrates AFP / Anne-Christine POUJOULAT

"You have taken me into your academy with open arms and you are a true inspiration to me. We all hope you continue for some more time."

Nadal, unbeaten in 13 previous finals in Paris and playing in his 30th Grand Slam decider, got off to a flying start against Ruud, the first Norwegian man to feature in a championship match at the majors.

He broke for 2-0 and even though he handed the break straight back courtesy of a two uncharacteristic double faults, he was quickly back in front again for 3-1.

The Spaniard wrapped up the opener in 49 minutes against his 23-year-old opponent who has trained at his academy in Manacor since 2018.

World number eight Ruud, the in-form player on clay since the start of 2020 with 66 wins on the surface, was under siege again in the second set, having to fight off three break points in the opening game.

There was a sudden glimmer of hope when he broke for 3-1 with Nadal again coughing up a double fault. However, Nadal roared back with a double break for 4-3.

Ruud saved three set points in the ninth game but his first double fault of the final handed Nadal a two-set lead.

Nadal had said on the eve of the final that he would rather lose Sunday's match in exchange for a new foot.

However, without needing to hit top gear, he was in complete control against Ruud, racing away to the title with three breaks in a third set which was over in 30 minutes.

Nadal sealed the win with a backhand down the line, his 37th winner of the final.

Earlier Sunday, Coco Gauff suffered a second heartbreaking French Open final defeat when she and American partner Jessica Pegula were beaten by Caroline Garcia and Kristina Mladenovic in the women's doubles final.

The French pair won 2-6, 6-3, 6-2 to add the 2022 title to their 2016 Roland Garros triumph.

On Saturday, 18-year-old Gauff had lost the singles final at Roland Garros in straight sets to Iga Swiatek of Poland.

"Hopefully, we can win one in the future," Gauff told the crowd and praised the atmosphere.

"The band was pretty cool, I thought I was at an American football game."