In elementary school science classes, we learned about a simple classification system used to group living things, and if I remember correctly, a favorite memory device our teachers used was “King Philip came from Germany.” browsing”.

If we were to divide sports into classifications, surely golf and tennis would share the same subdivision. So naturally, it was inevitable that shortly after Roger Federer and Rafael Nadal wrapped up their epic battle at Wimbledon on Sunday night London time, the comparisons and debate between the historic tennis match at the All England Club and the historic US Open golf tournament at Torrey Pines begin.

For five days and ninety-one holes, Rocco Mediate matched the incomparable Tiger Woods shot for shot. Over five sets, lasting four hours and forty-eight minutes, the 22-year-old Nadal traded booming groundstrokes with the 26-year-old Federer. Both events were equally compelling and historic on their own, but broken down into a smaller ranking, the people involved in Wimbledon give tennis a substantial advantage over golf.

The big difference between Woods and Jack Nickalus has always been and probably will continue to be the lack of a true rival, a forceful challenger to his throne who pushes him over the edge and legitimizes his greatness. Federer has found that in Nadal, but one could also argue that the young Spaniard has found it in the consummate Swiss champion.

Let’s take Mediate out of the equation for a second and insert Phil Mickelson at the 2008 US Open at Torrey Pines. Certainly, Mickelson’s presence would have created more of a stir in San Diego and left us with an even more memorable event for history. Without a doubt, golf has a harder time delivering No. 1 vs. No. 2 than tennis and even the BCS, but during the Tiger Woods era, it has happened much less frequently than during the Nicklaus, Arnold Palmer, and Gary Player era.

Some have called Woods’ victory at Torrey Pines the greatest performance in golf history. There are already cries that Nadal-Federer was the best match in tennis history. However, not even a Woods-Mickelson US Open double tops the story that the two greatest tennis talents have made.

For the comparison to be fair, Woods and Mickelson would have had to have played in the final pair on Sunday at the last three Masters and US Open. What is fair; Federer and Nadal have combined for six championship matches at the French Open and Wimbledon in the last three years.

Even if Federer, who is three Grand Slams away from eclipsing Pete Sampras’ record of 14 major titles, is Woods, Nadal is far superior to Mickelson. If Woods and Mickelson are No. 1 and No. 2 respectively, then Federer and Nadal are 1A and 1B and now that order is in question. The duo has dominated in an unprecedented way; Federer has led the rankings for a record 231 consecutive weeks, and Nadal has been a solid second with a record 154.

With Woods sidelined, Mickelson may still be out of a race this season. And the winner of this year’s tournament at Riviera Country Club and event at Colonial, who trails Woods by just over $1.8 million on the money list, may not even top Tiger in 2008 earnings. Nadal or Federer left the tennis scene for a year, the other would quickly rise to the top.

While Federer vs. Nadal is the tennis version of Yankees-Red Sox, Duke vs. UNC or even Magic vs. bird, woods vs. Mickelson is like any team that represented the NFC in the Super Bowl in the mid-’90s vs. the Buffalo Bills; technically a matchup pitting No. 1 vs. No.2 but with a practically predetermined outcome.

I’m not naive enough to think that golf can consistently give us the top two players in the world in close competition over the stretch of even half a season’s majors, but it would be nice to see them from time to time.

Maybe it’s just that Tiger is too dominant and an equal just can’t exist. But isn’t that what they said about Federer just a few years ago? Wasn’t Nadal supposed to just win on clay and make his mark as a single-surface specialist? Well, it turns out that the 22-year-old Nadal is just as tough mentally as Woods and Federer. Sorry, Lefty, but this southpaw has given tennis something our current era of golf will never appreciate: a true rivalry.

Woods’ painful performance at Torrey Pines will certainly go down as one of the greatest individual efforts of all time, but his official dance partner just doesn’t have what it takes to win the argument. As we saw on Sunday at Wimbledon, it takes two to tango and a truly epic battle ensues.