Their rivalry has been legendary even though Nadal seems to have the consistent edge.
Federer won the most recent match at the ATP tournament at Indian Wells despite faltering in the semis of the Australian Open.
What other rivalries can compare to this?
Here are the 25 greatest rivalries in the history of tennis.
These undersized stars gave every one of their opponents headaches.
When they played each other, each point seemed to be the result of a long and contested rally.
Agassi got the better of Chang, winning 15 out of their 22 matches.
Jennifer Capriati came into the WTA early on in her career and had her difficulties sustaining success.
She was better in her second tour of duty and used her guile, experience and strength to disrupt the Williams sisters from running away with the Tour.
Andy Murray may have won just 5 of his 18 matches against Nadal, but each time the two square off, fans are rewarded with classics.
With a new coach, Murray has broadened his game and beaten Nadal, albeit not on clay.
Patrick Rafter won his first Grand Slam, the 1997 US Open, by beating Andre Agassi.
From 1999-2001, they met in the Wimbledon semifinals three consecutive years.
Their 2000 match at Wimbledon is one of the most memorable matches in recent history. It was a classic duel, pitting a baseline expert against a serve-and-volley master, with Andre Agassi coming out on top.
There was no love lost between these two.
Justine Henin won five out of their first eight Grand Slam matches including every finals match.
Both women retired, only to come back a short while later to continue their rivalry.
The 2010 Wimbledon match capped their historic back and forth rivalry, with Clijsters winning the match and their rivalry 13-12.
Lleyton Hewitt was ranked No. 1 in early 2001.
Roger Federer would soon surpass him and keep a death grip on the position for years.
Kim Clijsters and Lindsay Davenport faced one another quite often in the early goings of Grand Slam tournaments with Clijsters narrowly getting the better of Davenport, 9-8.
One was known for his tenacity and quickness; the other was a Master Artist.
Though Sampras usually won, fans got everything they could ask for when these two faced each other.
Agassi and Courier's friendship dated back to their days at the Nick Bollettieri Tennis Academy.
In 1991, they met in the French Open final where Courier emerged with the victory.
At the end of their rivalry, Courier would hold the higher winning percentage, though Agassi would be the better and more popular player.
Venus Williams and Martina Hingis were two of the best players in the world, and their rivalry lived up to the hype. The duo met 21 times. Martina won 11, and Venus won 10.
Their rivalry was eventually cut short due to Venus' injuries and Martina's growing disinterest in the sport.
There was little doubt in tennis fans' minds that if they could have played each other more often, their rivalry would be remembered as one of the best the women's game has ever seen.
Sampras and Ivanisevic at Wimbledon was a feast for the service fanatics.
Games lasted just a few minutes, and if you were up from your seat, you may have missed a couple.
Their matches were always exciting and seemed to always go Pete's way. Sampras won in 1992, 1995 and 1998 against the Croat at Wimbledon.
Steffi Graf and Gabriela Sabatini played each other 40 times between 1985 and 1995 and Graf was the runaway winner.
Their 1991 Wimbledon final was arguably their most memorable match. Sabatini nearly had it in the bag, but Graf roared back and deprived Gaby yet again.
The two were friends off-court and paired up for doubles to make a formidable team.
Novak Djokovic and Rafael Nadal are the current top two players in the world and are engaging in a duel that is quickly approaching Nadal/Federer heights.
Both have played each other 30 times. Nadal leads the series 16 to 14 in match wins although Novak has defeated the Spaniard each of the last seven times.
The 2012 Australian Open final between the two was considered by many to be one of the best matches of the Open era.
It was Venus who took the lead but Serena was not to be left behind.
Serena leads the battle between the two 13-10 so far. In eight Grand Slam finals Serena leads 6-2.
They played each other in four successive Grand Slam finals—the only two women to do so.
Injuries, lack of motivation and a bunch of other factors have led these sisters astray.
Bjorn Borg and Jimmy Connors met 23 times during their careers on the ATP Tour (Borg winning 15 times).
Borg and Connors met at the US Open in 1975 and 1976, and Connors won both times.
The trend was reversed in Wimbledon (1977, 1978) when Bjorn Borg defeated Connors twice.
Borg was dominant over Connors during the latter part of his career, beating him repeatedly in Grand Slam matches.
Roger Federer remarked in 2009 that the Edberg-Becker rivalry in Wimbledon finals was his inspiration to choose tennis over soccer.
Becker and Edberg played each other 35 times!
Becker was the overall leader winning more than twice the matches he lost against Edberg.
The Grand Slam finals was different though—of the three they played on Wimbledon's greens, Edberg won two while Becker won his last Wimbledon beating Edberg.
Though Steffi Graf leads the head-to-head 10-5, it is not fair to say that she was dominant over Monica.
In Grand Slam finals, they won three matches each.
If Monica was not injured by a lunatic, she would have improved the record in her favor.
Graf was tested more often by Monica than anyone else during her stint as No. 1 on the WTA tour.
Boris Becker and Ivan Lendl played in 1986 when Becker was trying to defend his Wimbledon title.
They would meet in Grand Slams for other memorable occasions like the 1991 Australian Open which helped Becker to reach No.1 ranking.
A fast serve-and-volley player against a solid baseliner was a feast to watch. Lendl edged ahead 11-10 on overall matches between both players.
Steffi Graf and Martina Navratilova have met 18 times during their careers with the overall numbers standing at 9–9.
Steffi had a 4–2 record in Grand Slam finals while Navratilova enjoyed a 5-4 record in all Grand Slam matches.
Both appeared in three consecutive Wimbledon Singles finals (1987-89) to the enjoyment of tennis fans.
Ivan Lendl and John McEnroe played each other 36 times with Lendl edging ahead at 21-15.
Both met thrice in Grand Slam finals with Lendl winning twice. The most memorable meeting was at Paris in 1984, when Lendl came from two sets down to win.
It was interesting to note that at Wimbledon, both never met in a final.
Both were interesting personalities off-court, and the on-court rivalry kept everyone on their toes.
There have been 34 matches between Andre Agassi and Pete Sampras with Sampras winning easily by 20-14.
Of the five Grand Slam finals they played, Sampras was the runaway winner (4 wins to 1 loss).
Both of them played some incredible matches in Grand Slam tournaments. In the 2001 US Open quarterfinal neither player lost his serve.
The 2002 US Open final was their final match against each other. Sampras announced his retirement after winning the tournament.
A 15-year rivalry spanning 80 matches—arguably one of the greatest rivalries of all-time on women's tour.
Both played great matches with Chris dominating initially and Martina bull-dozing her way later on.
Chris was supremely consistent, but Navratilova was a robot who dominated like nobody else had.
Their matchups were consistently in the finals of the Grand Slam—no wonder—considering the talent they had.
These two met 34 times in a span of 15 years, across three decades.
McEnroe had an edge over his fellow American (20-14) even though the Grand Slam finals saw them win one each.
These were two great personalities who did not give an inch to the other on-court as well as off it, enlisting the support of everyone who could help (umpires, ball boys, spectators).
Undisputed legends they were!
Fire and ice.
McEnroe and Borg were contrasting personalities on-court who never gave each other an extra inch. They each won seven matches in their rivalry.
McEnroe won three finals in Grand Slam tournaments while in Wimbledon, the record was one-all.
The 1980 Wimbledon final that both of them featured in, was one of the greatest tennis match played at that time.
McEnroe defeated Borg in 1981 to end the Swede's run of 41 consecutive match victories at Wimbledon and hastened the retirement of Borg from active tournaments.
Roger Federer and Rafael Nadal form the all-time best rivalry in international tennis in the Open era.
Most of their matches have come on clay court, which has benefited Nadal, though to his credit, he has mastered Fedex on other surfaces also.
Nadal has a dominant record against Federer, even during the times when Federer was the undisputed king on the ATP tour.
They have played in every French Open and Wimbledon final between 2006 and 2008, shutting down the aspirations of all other players.
Their off-field friendship has been affected by the arguments of excessive play recently but that has not stopped a great rivalry from developing.
May they add to their existing records and entertain all of us!