* !Picby Pete Bodo*

Nothing testifies to the degree that most tennis matches boil down to a handful of key points, and the mental strength or weakness each player brings to those points, than the statistics.

In tennis, keeping statistics often seems akin to splitting hairs.

Consider this: As of this writing, the batting average for the top five hitters in the National League of Major League Baseball ranges between a league-leading .425 (Matt Kemp of the Los Angeles Dodgers) and .344 (Michael Bourn, Atlanta Braves). Granted, it's early in the year; by September, anyone hitting at .344 is already thinking contract re-negotiation.

Still, according to the ATP Ricoh Matchfacts, the top nine servers in tennis so far this year have a first-serve conversion percentage of between 69 and 72 percent—a swing of a mere three percentage points. Flavio Cipolla, Alex Bogomolov Jr., and Victor Hanescu are presently tied for the lead in that department. ATP No. 1 Novak Djokovic is serving at a 62 percent rate in 2012, placing him in a seven-way tie for bragging rights as the 33rd-best server on the tour.

As you go down the stats tables in tennis, entire rafts of players with identical numbers are the norm, not the exception. The stats show that tennis is a game of the tiniest margins, which suggests that the men who dominate have some quality other than a conspicous facility to doing some or most things far better.

Still, I was curious to see what we might glean from a comparison of those two great rivals, Djokovic and ATP No. 2 Rafael Nadal, if we compared them in the key statistical categories. And I wanted to look at their career numbers, not just year-to-date—at least on those categories where ranking is by percentage, and thus as representative as you can get for those players whose careers aren't complete.

You have to do a little data mining to get a clear picture in this enterprise, because of how bunched-up the players are, but this is what I came up with:

First-serve Conversion Percentage

Nadal:Fourth-best on the career list with 69 percent; tied with with two players, including countryman Fernando Verdasco, for No. 5 overall.

Djokovic: Ninth-best on the career list with 64 percent; tied with four other men, including Juan Carlos Ferrero. That puts him and those men at No. 30 on the overall list, given the number of players who share various higher percentages.

Read it and scratch your head: The all-time leader is, get this: Germany's Gilbert Schaller, who connected on 76 percent of his first serves.

First-Serve Points Won

Nadal and Djokovic: Tied as 11th-best with 72 percent—but both are no better than No. 88 when you count all the men who have a better percentage.

Read it and laugh out loud: The co-leader is ace-machine Goran Ivanisevic, who won a preposterous 82 percent of his first serves with that big, hooking lefty serve. (The other is Ivo Karlovic.)

!PicSecond-Serve Points Won

Nadal: No. 1, and tied with—guess who? (It's not Djokovic.) He's won 57 percent of his  second-serve points.

Djokovic: Owns the fourth-best percentage in this category at 54. But he's in pretty good company, tied for seventh overall with Thomas Muster and Andre Agassi.

Read it and get ready to argue: The man Nadal is tied with is Roger Federer.

Service Games Won

Nadal: Seventh-best with an 85 percent success rate, tied with four other men, including Ivan Ljubicic, for 12th overall.

Djokovic: Eighth-best with 84 percent, tied with nine men.

Read it and and ask, "Who' that?": Wayne Arthurs is No. 5 on this list, at 88 percent.

Break Points Saved

Nadal: Fourth-best, tied with six other players.

Djokovic: Fifth-best, tied with four others.

Read it and tip your hat to these two:This list reads like a who's who of great servers, starting with Karlovic, John Isner, and Andy Roddick. Nole and Rafa are in some heady company here.

First-Serve Return Points Won

Nadal: Second-best percentage with 34%, a record shared with 11 other players.

Djokovic: Third-best at 33 percent, tied with 10 other players.

Read it and say, "I see what you mean. . .": Just look at how little separates the two men—again.

Second-Serve Return Points Won

Nadal:Second-best 55 percent success rate. One among nine with that percentage.

Djokovic: Third-best 54 percent success rate. One of 14 players with that percentage.

Read it and shout, "No way!": Byron Black is one percentage point better than Djokovic.

Break Points Converted

Nadal and Djokovic: For the second time, a dead heat at 45 percent, along with six others.

Read and try not to act surprised: Nobody was better in this department than. . . Guillermo Coria (46 percent).

Return Games Won

Nadal: Comes in at No. 2, with a 33 percent career rate.

Djokovic: Fourth-best 31 percent career rate, tied with eight others.

Read it and go Hmmmm. . .: Given the slight margins we've been dealing with here, this one seems dramatically significant, not least because Coria (the not-so-surprising leader once again) stands alone, as does Nadal, after which eight men boast a 32 percent success rate, and nine (including Djokovic) are at 31 percent.

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So what do we make of all this? First of all, Djokovic and Nadal are already well-entrenched among the best players ever to play this game, at least statistically, but. . . let's remember that while longevity is not an issue when it comes to percentages, it can influence those numbers as a player continues beyond his peak years. However, that effect seems to be modest (the 30-year-old Federer is among the all-time leaders in every department as well).

You have to be impressed by just how close these rivals are in all these tables. Rafa and Nole are separated by more than two places in only two of these departments. The widest gap between the men is first-serve conversion percentage, followed by second-serve points won.

Overall, Nadal still has a very small but distinct edge on Djokovic in almost every department. You could easily dismiss those fractional differences and argue that our concept of margin-of-error wipes them out—if you didn't know what a fine line so often separates the winner from the runner-up in tennis.