Rafael Nadal is gaining on Roger Federer. Quickly.
By winning four of the past five Grand Slam tournaments, capped by a victory over Federer in Sunday's French Open final, Nadal has raised his career haul to 10 major championships. That's only six fewer than Federer's proudly held record of 16.
"Ten Grand Slams is a lot," Federer said. "He knows this.
"I know this. Everybody knows this."
Seven men in the history of tennis have managed to win at least that many: Federer, Pete Sampras (14), Roy Emerson (12), Bjorn Borg (11), Rod Laver (11), Bill Tilden (10), and Nadal.
Of that group, only Borg was younger when he cradled his 10th Grand Slam trophy than Nadal, who was two days past his 25th birthday when he beat Federer 7-5, 7-6 (3), 5-7, 6-1 Sunday at Roland Garros.
Nadal's six French Open trophies, tying Borg's record for the most in Paris, now sit alongside two from Wimbledon and one apiece from the U.S. Open and Australian Open.
"If I win this tournament, I know my year is fantastic," Nadal said Sunday evening.
"You are able to play with less pressure the rest of the season. You are able to keep playing … with the same positive attitude … but with less pressure than before and with better confidence than before."
When Federer was winning Grand Slam title after Grand Slam title — three per season in 2004, 2006 and 2007, for example — many assumed it was the sort of display that wouldn't be duplicated, at least not any time soon.
But Nadal is putting together the same sort of run, with two major championships in 2008 and three last season. The Spaniard is about six months younger than Federer was when he collected his 10th Grand Slam title at the 2007 Australian Open.
Nadal leads their head-to-head series 17-8. More significantly, Federer is 2-6 against Nadal in major finals, 14-1 against everyone else. That's part of why the Grand Slam gap between them is narrowing: Not only is Nadal picking up titles, he's also preventing Federer from adding to his total.
All of which leads some to say that Nadal is on his way to being the one considered the best tennis player in history.
Andre Agassi, for one, thinks that discussion is still open.
"While Rafa can say, 'He might be the best of all time, but I beat him and I was better than him,' I do believe that you have to leave a little room for matchup," said Agassi, who retired in 2006 with eight Grand Slam titles.
"Some people can just be inherently at a disadvantage based on a certain style of play."
"Will it take Rafa as many Slams to prove that he's better than Roger?" asked Agassi, who completed his career Grand Slam by winning the 1999 French Open.
"I don't think so. But you have to separate yourself from the field.
"That's what makes somebody great: how far you separate yourself from the field, across all surfaces. Rafa's won a couple at Wimbledon.
"Roger, if not for Rafa, would have won four or five [at Roland Garros]. I think Roger has separated himself from the field more in his time than Rafa has done yet.
"But there's still time for Rafa."
Now they move to Wimbledon, where Nadal is the defending champion and won the title each of the past two times he entered the tournament (he withdrew in 2009, citing a knee injury).
Nadal, who kept his No. 1 ranking Monday thanks to his French Open championship, was heading straight from France to England, where he will make the transition from clay to grass at the Queen's Club tournament.
"Always a big change," he said. "Even if I had success on grass [in past] years, for me, [it's] a big change all the time.
"So I have to adapt my game another time and try to remember what I did well on grass, why I played well on grass, what I have to do to have the same feeling."
Play starts at Wimbledon in two weeks and, in addition to tracking Nadal there, tennis fans will want to keep a close eye on two other men: Federer and Novak Djokovic.
Until losing to Federer in a thrill-a-minute French Open semifinal, Djokovic was 41-0 in 2011 and on a 43-match winning streak overall. The 24-year-old Serb has won two Australian Open titles, in 2008 and this January, but he has yet to go beyond the semifinals at Wimbledon.
Djokovic also is 4-0 against Nadal this season, and would have moved up from No. 2 to No. 1 in the rankings if he'd gotten past Federer on Friday or if Nadal had lost on Sunday.
And Federer? Well, all he's done at Wimbledon is take home six titles, one shy of Pete Sampras' modern-day mark.
"That's, obviously ,the huge priority right now — to win Wimbledon in a few weeks time," Federer said. "That's always, for me, the sort of No. 1 goal in the season.
"This is where it all started for me back in 2003."
While he lost in the Wimbledon quarter-finals a year ago, Federer proved in Paris that, even as his 30th birthday in August approaches, he is still someone to be reckoned with.
"It was just important to get to another Grand Slam final, keep on playing well," said Federer, who had gone more than a year without reaching the title match at a major tournament, his longest gap since he won his first Grand Slam title at Wimbledon eight years ago.
"I'm feeling better physically than I have in a long time, so that's been very positive."
Who knows how many more Grand Slam titles he'll collect?
And what about Nadal?
After Sunday's final, a reporter asked Toni Nadal, Rafael's uncle and coach, how big a deal it was to have won six French Opens.
"When his career is over, there will be time to reflect," Uncle Toni said. "But right now, I think Rafael thinks the sixth is the same as the second.
"We're happy to have won one more tournament, to have won one more Grand Slam title. And now he has 10, something we never imagined."