Novak Djokovic and Rafael Nadal clash for the 58th time on Friday on the same court where they first met 15 years ago with a place in the French Open final at stake. It is tennis's greatest modern rivalry between two men who have harvested 38 Grand Slam titles between them and 72 Masters.
Djokovic has spent more weeks at world number one than any other player while 13-time French Open winner Nadal has not been out of the top 10 in 16 years.
Nadal will start Friday's semi-final as favourite, buoyed by his record of 105 wins and just two losses in his Roland Garros career.
The 35-year-old also has the edge over Djokovic on clay with a 19-7 career lead and 7-1 in Paris.
Djokovic hasn't beaten Nadal on the surface since Rome in 2016.
He can, however, boast being one of only two men to have defeated Nadal in Paris, in the quarter-finals in 2015.
"It's a well-anticipated semi-final and here we are," said Djokovic of a rivalry which started on Court Philippe Chatrier in 2006.
"We had some battles over the years on this court."
Nadal defeated 2016 champion Djokovic in straight sets in last year's final, the Serb's third loss in the championship match in Paris to the Spaniard.
There is plenty at stake on Friday as the two rivals close in on Sunday's final.
Djokovic can win a 19th Slam and become the first man since Rod Laver in 1969 to win all four Slams twice.
Victory for Nadal would give him a record-setting 21st major, breaking the tie with Roger Federer.
"The vibes are different walking on the court with him," added Djokovic. "But that's why our rivalry has been historic."
It's been a topsy-turvy tournament for Djokovic.
After racing through the first three rounds, he had to come back from two sets down to defeat Italian 19-year-old Lorenzo Musetti.
In the quarter-finals, he dropped the third set against Matteo Berrettini.
With the exception of a second-set blip in the quarter-finals against Diego Schwartzman, Nadal has reached his 14th semi-final relatively unscathed.
Despite his clay court stranglehold on Djokovic, Nadal isn't getting too far ahead of himself.