By Matt Brown in Paris
When Rafael Nadal and Roger Federer square off overnight in the men's semifinals at Roland Garros, it will be their 39th career meeting.
The Spaniard has won 23 matches to 15, with 12 of those wins on clay to Federer's two on the surface. However, Federer has won their last five matches with the last time they met coming in Shanghai in October 2017.
Nadal is gunning for a 12th Roland Garros title. He has lost here just twice since 2005 with his record standing at 91 wins and 2 defeats. Only twice has he been pushed to five sets in Paris. It would seem like mission impossible for Federer who lost the 2007, 2008, 2010 and 2011 finals to Nadal at Roland Garros along with the semifinal in 2006. Surely in 2019, Federer who turns 38 in August and hadn't played on clay since 2015 prior to his return in Madrid last month, doesn't stand a chance against the King of Clay?
There is a school of thought going around that Federer actually has the best chance he's ever had of dethroning Rafa. Craig O'Shannessy is a leading tennis strategy analyst who does work for the ATP Tour, grand slams and is part of world number one Novak Djokovic's wider team.
He notes some key differences in Federer's game now to when they last met on clay in 2013.
"Rafa will serve a lot to the backhand. It's all going to depend on Roger coming over and popping that backhand return. It's also going to depend on Roger coming over and popping that backhand return," O'Shannessy said.
Before Federer won the 2017 Australian Open final against Nadal, he almost exclusively employed a slice backhand return and it was more of a defensive shot than an attacking weapon.
"It's also going depend on where he hits the return. If he hits it right back to Rafa's backhand, he is so good at blocking that return. So he has to go to the forehand side and Roger also has to serve and volley a little bit."
He served and volleyed 60 times against Stan Wawrinka in the quarter-final.
"Roger is coming forward well, and he has to take the time away from Rafa. If he does that and pushes Rafa out wide to the forehand and rallies a little bit to the backhand, and keeps the rally length short, he has a real chance.
"The world does not think that Roger Federer has a chance. But if he plays the right way and takes away Rafa's run around forehand he absolutely has a chance."
Still, the smart money has to be on Nadal who remains a firm favourite but only a fool would completely write Federer off.
Matt Brown is in Paris courtesy of Emirates Airline