Andy Murray thinks Rafael Nadal's 13 French Open titles is among the greatest achievements in sporting history and one that will never be topped.
Nadal's victory over Novak Djokovic on Sunday means the Spaniard has won five more titles than any other male player at a single grand slam and two more than Margaret Court's record at the Australian Open.
He also equals Roger Fereder's record of 20 grand slam titles at the top of the men's all-time list.
"It's an amazing achievement," said Murray, who was speaking to reporters ahead of an ATP 250 event in Cologne, according to Reuters.
"I don't think what he has done at Roland Garros will ever be beaten. He's one short of winning the same amount at just one tournament as Pete Sampras did in grand slams.
"I think it's one of the best records in sport, maybe the best. I don't think it will ever be repeated and I actually don't think anyone will get close to it."
Three-time grand slam winner Murray has twice beaten Nadal at majors but has suffered two defeats to the world No. 2 at the French Open.
Only Djokovic in 2015 and Robin Soderling in 2009 can lay claim to defeating Nadal at the clay major.
Murray, who lost to Stan Wawrinka in the first round of this year's French Open, said he thinks Djokovic or Nadal could end up outstripping Federer in the all-time list.
"Providing they all stay fit and if they retire all at the same age, then I would think it would be between Rafa and Novak," said Murray, when asked who of the "Big Three" could capture the most grand slam titles.