Rafael Nadal has been described by many as the greatest clay-court player ever - and victory over Roger Federer in Paris on Sunday made the statistical case even stronger.
The Spaniard drew level with Bjorn Borg, his only rival for the title as 'King of Clay', on a record six French Open titles and at the age of 25 there is every chance he will pass the Swede in years to come.
Borg shocked the tennis world by quitting at a similar age as the reigning French Open and 11-time Grand Slam champion, leaving open the question of how many more times he could have won at Roland Garros and elsewhere.
One man who experienced standing across the net from the Swede in his pomp was former British number one John Lloyd, who beat an 18-year-old Borg on clay in Monte Carlo in 1975.
Lloyd, who has been working with BBC Sport on Court Philippe Chatrier to watch Nadal accumulate his French Open titles, compares the two greatest clay-courters.
To me, Rafa's forehand on clay is the greatest shot in men's tennis and has been for years, because of the pace, the angles he creates and the spin he gets on it.
Roger's struggled with it because he's a one-hander and to come over that ball he either has to hit it early and take it on the rise - and to time that for three or four hours is almost impossible - or step further back and go 6-8ft behind the baseline.
But then if you don't return it to an unbelievable length, Rafa's inside the court and just pulls you around with the forehand.
With Bjorn, to pick one shot would be difficult but I would probably say his forehand.
For someone like myself to have any chance I knew I was going to have to get into the net, because I wasn't going to beat him from the back.
The problem was he had unbelievable passing shots and could run them down so quickly. You had to hit your volleys perfectly to have any chance of beating him. He was brutal.
FITNESS AND MOVEMENT
I always felt speed and stamina were Bjorn's greatest strength. He got to every ball. He was the quickest and fittest player I ever played by miles.
You could never tire him out; there was no chance of that. I spoke to Bjorn once, years after he retired, and asked him if he ever got tired in a match. He said: "Well, I remember one time when I played Lendl and it was 5-5 in the fifth and I got tired for a few seconds." And I believe him.
I'd say Rafa is the closest you could ever get to Bjorn on this - he's in incredible shape - but to me Bjorn was bionic and he didn't need to work out 12 hours a day. It came naturally to him.
For me, he was the greatest athlete that ever played the game and I'd love to have seen an all-round endurance contest with Rafa. Take away the racquets and go at it - that would have been fun to watch.
Bjorn might have appeared silent and ice cool but he wasn't like that at all off court. On court he was absolutely deadly because he had the same expression whether he was up a set and a break, or down a set and a break.
You looked over at him and he looked back as if to say, "You've still got to close out the match, I'm still here and I'm not going anywhere". Whether he missed a couple of balls or not, he still gave you that steely look, "You've still got to hit another one, and another one, and another one…".
Rafa's the same. They're both brilliant that way. He's in your face, tries every point. I couldn't separate those two in that way, both incredible.
With Bjorn, particularly on clay, basically you were beaten before you went on court if it was over five sets because you knew he could stay out there all day.
You either had to try to hit him off the court - good luck with that, especially with wooden racquets - or try to beat him by staying out there. Good luck again. I wasn't a baseliner and came in for a quick death, then got the hell out of there.
Against the really good baseliners, he would wear their legs out like a boxer over 15 rounds and after a set and a half they were gone. Rafa has a similar fear factor, although he wasn't actually hitting the ball as well as he can at the beginning of the fortnight in Paris.
He rebounded brilliantly and was playing close to his best by the end. Rafa's lost one match in seven years at the French - I'd say the other guys fear him.
When Bjorn finished, he had started to lose a bit to McEnroe but that wasn't on clay. He could have won another two or three French Opens easily and, for me, I still think he's the greatest clay-court player of all time. Rafa hasn't nudged him yet for me, but then I'm from that era so I'm biased - and Rafa's got plenty of time left anyway.
AND ON BEATING BORG ON CLAY...
I think he'd had a very late night. I remember winning it, I don't remember much else. I did play very well, and he took it well, but I never asked him afterwards if he had been out the night before because I didn't want to burst my bubble.
I told everybody I played great and I was just too good for him. It's a pretty good thing to have on your CV, but no-one believes it - they all think he must have been ill!