Novak Djokovic and Rafael Nadal meet for the 56th time on Sunday in the French Open final.
AFP Sport looks at six of their best Grand Slam matches:
When Djokovic won:
Australian Open final
Djokovic 5-7, 6-4, 6-2, 6-7 (5/7), 7-5
-- In the longest ever Grand Slam final at five hours and 53 minutes, Djokovic came back from 4-2 down in the fifth set. It was the third successive Grand Slam final that Djokovic and Nadal had contested, and saw the Serb extend his winning streak over Nadal to seven straight matches.
"I think it comes out on the top because, just the fact, that we played almost six hours is incredible," said Djokovic when asked if it had been his greatest ever match.
An exhausted Nadal added: "Physically it was the toughest match I ever played."
2015 Roland Garros quarter-final
Djokovic 7-5, 6-3, 6-1
-- Djokovic became only the second man after Robin Soderling in 2009 to defeat Nadal on the red clay of Roland Garros as he maintained his hopes of completing the career Grand Slam.
Djokovic was to lose the final to Stan Wawrinka but would win his first Roland Garros title 12 months later with a victory in the final over Andy Murray.
"It's definitely a big win, a match that I will remember for a long time," said Djokovic.
"He was better than me. That's it. It's very simple," said Nadal who was celebrating his 29th birthday.
2018 Wimbledon semi-final
Djokovic 6-4, 3-6, 7-6 (11/9), 3-6, 10-8
-- Just weeks before Wimbledon, Djokovic had suffered a shock quarter-final exit at the French Open at the hands of Marco Cecchinato, the world number 72 from Italy, and had even threatened to skip the grass court Grand Slam.
The semi-final was another classic with Djokovic saving five break points in the fifth set before triumphing after five hours and 15 minutes.
"One of the longest matches of my career. I am overwhelmed," said Djokovic.
Nadal said: "I have not much more inside me. I gave it my best."
When Nadal won:
2012 Roland Garros final
Nadal 6-4, 6-3, 2-6, 7-5
-- In a final that was played over two days due to several rain delays, Nadal hit 34 winners to 29 unforced errors, and led two sets and a break before the Serb took eight consecutive games and a 2-1 lead with a break into the third Monday.
When played resumed, Nadal broke back and went on to wrap up victory in three hours and 49 minutes.
"It is an honour and for me the most important tournament, the greatest in my eyes. This is an unforgettable moment," said Nadal.
Djokovic added: "The playing conditions were not good. But it's not anybody's fault, and it's not the reason why I lost today."
2013 Roland Garros semi-final
Nadal 6-4, 3-6, 6-1, 6-7 (3/7), 9-7
-- Djokovic was trying to become the eighth man to complete the career Grand Slam while Nadal was bidding for an eighth title in Paris. Djokovic had earlier in the season defeated the Spaniard on clay in Monte Carlo, ending Nadal's 46-match win streak.
In the Roland Garros final, Nadal was 6-5 up in the fourth set and two points from victory but Djokovic hit back and then led 4-2 in the final set before Nadal dug deep to triumph after four hours and 37 minutes.
"I want to congratulate Novak, he's a great champion and he will win here at Roland Garros one day, I'm sure," said Nadal.
World number one Djokovic added: "It's been an unbelievable match but all I can feel now is disappointment. I congratulate him, that's why he's a champion."
2014 Roland Garros final
Nadal 3-6, 7-5, 6-2, 6-4
-- Nadal again prevented Djokovic from completing a career Grand Slam as he became the first player to win nine titles at a major. It was also his 14th Slam trophy.
Despite taking the first set, the final ended in a whimper for Djokovic who double-faulted on championship point.
Djokovic admitted that Nadal was probably the fresher player as the final progressed in brutal 30-degree heat.
"For me, the most important tournament, the greatest in my eyes," said Nadal.
Djokovic said: "I was not at the level I was at when I beat him in Rome last month. It takes it out of you. Rafa was the better player."