Imagine Tiger and Jack playing in the same era, trading major titles at Augusta, Pebble Beach and St. Andrews. Or how about Jordan's Bulls and Russell's Celtics battling each other for titles every spring, year in year out? Or what about if Montana's 49ers of the 80's overlapped with Aikman's Cowboys of the 90s?

Here's what you'd get: Men's professional tennis for the past seven years. Arguably the sport's two greatest players of all-time have coexisted in the same era. And this past weekend's French Open Final was no letdown to the legacy.

Since 2004 at Wimbledon, there have been 28 Grand Slam championships. Roger Federer and Rafael Nadal have combined to win 24 times. Eight of the finals have featured a Federer-Nadal match-up and 25 have included at least one of the two.

Overall, the rivals have met in the finals of 19 different events for a total of 25 head-to-head matches (Nadal leads the series 17-8). Federer has won 16 Grand Slam titles, while Nadal added his tenth with a victory at the French.

This begs the question, "What if the opposing competitor did not exist during the same era?"

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In Federer's case, his all-time record of 16 Grand Slam Championships would be even greater. Nadal has denied Federer seven times in Grand Slam Matches (six finals), including five bouts on Centre Court in Paris. It is not farfetched to assume that Federer would have at least three or four more Grand Slam titles if it were not for the southpaw Nadal wearing him down.

Nadal dethroned Federer as the No. 1 player of the world in August 2008 after Federer held the spot for four and half years since February 2004. Without Nadal, Federer would have cruised to upwards of 20 major titles and even longer reign as the world's No. 1 player. However, with Nadal's competition, Federer was kicked off the top of the podium and lost a year or two of his prime to fatigue.

In Nadal's case, Rafa has lost two finals to Federer (both at Wimbledon), depriving him of a pair of major titles and maybe the best start to a career in tennis history. After defeating Federer on hard court in March 2004 and March 2006, Nadal did not defeat Federer on a surface other than clay again until July 2008 on grass at Wimbledon in a five-set thriller.

It was not until January 2009 that Nadal was finally able to oust Federer again on hard court at the Australian Open. While Nadal has been Federer's kryptonite on clay, Federer has done his best to do the same to Nadal on hard court and grass. Nadal is 12-2 against Federer on clay, but only 5-6 against the Swiss opponent on hard/grass.

There are the naysaysers that question Roger and Rafa's legacy. From time to time, the duo hears the argument that the competition may just be weak in their era.

But that accusation is beyond false. The consistency of Federer and Nadal's rivals has proven that this is not the case. Unlike any other era before them, Federer and Nadal have seen the same common suspects in practically all of their Grand Slam Runs. Players like Andy Murray, Robin Soderling, Tomas Berdych, David Ferrer, Gael Monfils and Stanislas Wawrinka have all hung around the ATP Top 10 throughout the Federer/Nadal era, but none of them have gained enough steam to slip by both players for a Grand Slam title.

Heck, Andy Roddick, the lone American Top 10 stalwart of the era, is 5-26 against Roger and Rafa. Novak Djokovic has slipped by for two majors and was gaining momentum (43 consecutive victories) before Federer ousted him at last week’s French Open semifinals. For the tenth time in his career, Djokovic was knocked out of a Grand Slam event by either Federer or Nadal, neither of whom prepare to let Djokovic steal the limelight in the second half of their historic rivalry.

Assuming the 25-year-old Nadal continues to dominate the sport in his prime, he should easily pass Pete Sampras' second-place total of 14 Grand Slam titles. The 29-year-old Federer will continue to attempt to increase his record 16 titles as long as he can stay healthy. Either way, it appears that Federer and Nadal will come out of the same era as No. 1 and No. 2 in tennis' most prestigious category: Grand Slam titles. In perspective, it may be the most remarkable statistic in professional sports that two players in the same time period can set records in the game’s defining statistic.

The Lakers and Celtics of the 80's give Federer and Nadal a run for their money, as the two NBA clubs won eight of nine titles from 1980-1988 with three head-to-head finals. However, neither team holds the record for most titles in an era, as the Celtics won 11 championships from 1957-1969 and the Bulls won six titles from 1991-1998. Federer and Nadal will come out together with the most Grand Slam titles in their era and of all-time.

Tennis fans sometimes point to the Björn Borg-John McEnroe rivalry of the early 80's as a similar one to that of Federer and Nadal. However, Björn's 11 and McEnroe's seven major titles, as well as the duo's four Grand Slam finals meetings will be shattered by Federer's and Nadal's final stat lines.

As the elder Federer gears up for his last burst, we will see the final years of the (quietly) greatest era of any sport in athletics history. The sports world may never see the two greatest teams or players of all-time coexist in the same sport in the same era.