Novak Djokovic said he never doubted he could launch a dramatic fightback from two sets down to beat Stefanos Tsitsipas in Sunday's French Open final and claim a 19th Grand Slam title and become the first man in 52 years to win all four majors twice.
The world number one triumphed 6-7 (6/8), 2-6, 6-3, 6-2, 6-4 over the Greek 22-year-old who was playing in his first Slam final.
His victory over four hours followed having to also play four hours to beat 13-time champion Rafael Nadal in the semi-finals on Friday.
"I have played almost nine hours over the last 48 hours against two great champions, it was really tough physically over the last three days, but I trusted in my capabilities and knew I could do it," said the 34-year-old Djokovic.
"It was an electric atmosphere. I want to thank everyone who has been with me on this journey."
Djokovic is now just one major away from equalling the all-time record of 20, jointly held by Roger Federer and Rafael Nadal.
He has time on his side. He is a year younger than Nadal and has the best part of six years on Federer.
Sunday's victory also put him halfway to a rare calendar Grand Slam.
It was a second French Open crown for Djokovic after his 2016 victory and adds to his nine Australian Opens, five Wimbledon titles and three at the US Open.
He is the first man since Rod Laver in 1969 to win all four Slams on multiple occasions and just the third in history.
"I would like to say a few words to Stefanos. I can relate to what he's going through and I understand how difficult it is to lose in the final," said Djokovic who has lost four finals in Paris - three against Nadal and one to Stan Wawrinka.
"These are the kind of matches you learn from most and knowing him and his team, he will come out much stronger.
"I definitely believe he will win many Grand Slams in the future."
Tsitsipas hailed Djokovic as a great champion as his first Slam final appearance ended in a heartbreaking defeat having been in command for the first two sets.
It was his third successive loss on clay to the Serb after they played a five-set semi-final at the 2020 French Open and the quarter-finals in Rome on the eve of this year's French Open.
"I tried my best," said weary-looking world number five Tsitsipas.
"I had a good run and am happy with myself, but let's give it to Novak because he has shown us over the past couple of years what a great champion he is.
"I am inspired by the things he has achieved and I hope one day I can maybe do half of what he has done so far."
Both men won praise from Swedish legend Bjorn Borg who presented the trophies.
Borg won the French Open six times in a career which yielded 11 Grand Slam titles.
"To see these two great champions and watch these guys is unbelievable," he said.
"Unfortunately tennis is a tough sport, it is only one winner. Perhaps it should be two."