© Getty ImagesRoger Federer and Rafael Nadal contested what Sports Illustrated later proclaimed to be the greatest match ever in the 2008 Wimbledon final.

1. Roger Federer vs. Rafael Nadal

Given Roger Federer's domination of the decade, it's almost frightening to contemplate what other records he would have set had it not been for the emergence of Rafael Nadal, with whom the Swiss shares one of tennis’ greatest-ever rivalries. Since winning their first meeting at the Sony Ericsson Open in 2004, Nadal has established a 13-7 head-to-head lead over Federer, with 16 of those 20 meetings coming in ATP World Tour and Grand Slam championship finals.

Different in so many ways, they nonetheless share an unparalleled will to win that has made for some riveting clashes – none more so than what many fans rate as the greatest match ever, the 2008 Wimbledon final. Nadal has held Federer’s number in three Roland Garros finals, and it looked as though the Swiss would always get his revenge on grass, having denied Nadal in the 2006-07 Wimbledon finals. That was until a rain-interrupted clash that finished in near-darkness at 9:15 p.m., when Nadal prevailed 9-7 in the fifth set of a four-hour, 48-minute match to dethrone the five-time defending champion.

They have played just twice since that epic encounter, with Nadal once more besting Federer over five sets in the 2009 Australian Open final and the Swiss defeating Nadal on clay for just the second time in the final of the Mutua Madrilena Madrid Open a few months later.

2. Pete Sampras vs. Andre Agassi

Pete Sampras and Andre Agassi contested just six of their 34 career meetings in the decade, but they had three very memorable clashes at Grand Slam level. (Interestingly, Agassi and Sampras met a total of just seven times in Grand Slam play during their rivalry from 1989-2002.)

In the 2000 Australian Open semi-finals, Agassi came from two-sets-to-one down to beat Sampras 6-4, 3-6, 6-7(0), 7-6(5), 6-1 en route to the title. Sampras, who hit 37 aces, routed Agassi 7-0 in the third-set tie-break and was within two points of victory when serving at 5-4 in the fourth-set tie-break. In the same year Agassi enjoyed a straight-sets win over Sampras in the Indian Wells and Los Angeles finals – notching a three-match winning streak against the six-time ATP World Tour champion for the first and only time in his career. Agassi also narrowed his head-to-head deficit against his arch rival to a 14-17 win-loss record and looked capable of levelling the series.

But Sampras would have the final say, winning their last three encounters. A fourth meeting in 2001 in the US Open quarter-finals was one of the best matches of the decade, if not of all-time. Played under lights in front of a highly-engaged New York crowd, neither player dropped serve in a match that featured tie-breaks in all four sets. Before the start of the fourth-set ‘breaker, the crowd rose as one to cheer the two combatants, who left nothing on the court. Agassi made just 19 unforced errors in the match but couldn’t crack the steely focus of Sampras, who by match’s end had held serve for 87 consecutive games in the tournament.

Fittingly, it was Agassi on the other side of the net in the final match of Sampras’ career: the 2002 US Open final. Having endured a two-year, 33-tournament title drought (stretching back to Wimbledon 2000), 31-year-old Sampras battled his countryman for the trophy both wanted so badly. A beaten finalist the previous two years, Sampras knew that this was likely his last chance to extend his then-record haul of Grand Slam titles to 14. Sampras served up 33 aces and saved break points in two games in a dramatic fourth set to win 6-3, 6-4, 5-7, 6-4 to extend his perfect US Open record against Agassi to 4-0.

3. Rafael Nadal vs. Novak Djokovic

In just over three-and-a-half years, Rafael Nadal and Novak Djokovic have already clashed 21 times, with the Spaniard coming out on top on 14 occasions. Nadal has won all four of their meetings in ATP World Tour Finals and has never lost to the Serb on clay (9-0), including a memorable victory in the semi-finals of the Mutua Madrilena Madrid Open this year. In the longest best-of-three-set match on the ATP World Tour in Open Era history, Nadal and Djokovic delivered on the potential of their rivalry with a pulsating four-hour, three-minute clash that saw the Spaniard save three match points to edge victory. The devastating defeat for Djokovic did not knock the wind out of his sails, though; as he went on to win his following three meetings with Nadal – all in straight sets on hard courts

4. David Nalbandian vs. Roger Federer

David Nalbandian is one of very few players who can boast a competitive head-to-head record with Roger Federer, only trailing the Swiss maestro 8-10 since their first meeting at the Monte-Carlo Rolex Masters in 2002 – when he crushed Federer for the loss of just three games. On his day, Nalbandian is more than a match for Federer and has held the Swiss’ number on the biggest of stages.

The Argentine recorded the biggest win of his career as he rallied from a two-set deficit to top Federer in a fifth-set tie-break in the final of the 2005 Tennis Masters Cup (now known as the Barclays ATP World Tour Finals) and, during a hot streak for Nalbandian at the close of 2007, Federer twice more fell victim to his Argentine rival with back-to-back losses at the ATP World Tour Masters 1000 tournaments in Madrid and Paris. Those three victories were anomalous with the pattern the rivalry had been following, though. Since winning their first five clashes, Nalbandian had begun to fall away from Federer and has lost seven of their past 10 meetings.

5. Patrick Rafter vs. Andre Agassi

Pat Rafter and Andre Agassi played three of the most memorable Grand Slam semi-finals of the decade. With the Australian’s athletic serve and volley style pitted against the lethal Agassi returns and passing shots, theirs was one of the most entertaining and compelling rivalries the game has seen. Rafter won back-to-back five-set semi-finals over Agassi at Wimbledon in 2000-01. In the latter clash, Agassi served for the match at 5-4 in the fifth only to see Rafter break back and eventually win 2-6, 6-3, 3-6, 6-2, 8-6. The stage, the contrasting styles and extraordinary quality of tennis compelled both men to play some of their best-ever tennis.

At the Australian Open in 2001, Rafter had his sights set on snapping a then-25-year title drought for Australian men at their home Grand Slam. With unheralded Frenchman Arnaud Clement waiting in the final, the Rafter-Agassi clash was widely considered to be the defacto final. After three high-octane sets in which he attacked the net at all costs, Rafter held the edge as Aussie fans whipped themselves into a frenzy. But Rafter was losing so much sweat that he started to suffer from cramps while the super-fit Agassi reaped the benefits of his grueling pre-season with fitness guru Gil Reyes in Las Vegas. Agassi went on to win 7-5, 2-6, 7-6(5), 6-2, 6-3.

In other key meetings, Agassi easily ousted Rafter in the 1995 Australian Open fourth round en route to the title. And Rafter beat Agassi in four sets in the 1997 US Open fourth round en route to the first of his back-to-back crowns at Flushing Meadows.

Agassi finished with a 10-5 edge in their 15 meetings between 1993 and 2001.

Fabrice Santoro vs. Marat Safin

Call this a guilty pleasure, but the Fabrice Santoro-Marat Safin rivalry is one of the most perplexing head-to-head series the game has seen. Santoro’s double-handed slice-and-dice chicanery drove Safin to within an inch of his sanity during his career. Looking at their games, Safin had an overwhelming advantage in shot making firepower, not to mention in physical presence. But Santoro had cunning.