I always scoff at the notion that Tiger Woods' dominance over golf is more impressive than what Roger Federer has done in the tennis world. Tiger has been out of contention and even missed the cut at majors over the past four years, whereas Federer has finished out of the top two once in that period.
And considering the tennis season is 11 months, just for a player to be healthy enough to play in a record 23 consecutive Grand Slam semifinals, as Federer has, is a feat we might never see again. Just look at his rival Rafael Nadal.
But beyond their accomplishments and the physical toll of the games these men play, the main reason I give the nod to Federer over Tiger is that I believe no sport demands more mentally from an athlete than professional tennis.
Andre Agassi's autobiography, "Open," caused quite a stir this past fall with all those tidbits about crystal meth, hair weaves and Pete Sampras' bad tipping habits.
But there was a less controversial passage in the book that really resonated with me:
Tennis is the sport in which you talk to yourself. No athlete talks to themselves like tennis players. Pitchers, golfers, goalkeepers, they mutter to themselves, of course, but tennis players talk to themselves -- and answer ... Why? Because tennis is so damned lonely ... of all the games men and women play, tennis is the closest to solitary confinement.
Anyone who has ever played competitive tennis, even on a recreational level, has some sense of what Agassi was talking about. Watch the self-dialogue Federer and Serena Williams engage in this weekend as they play for Australian Open titles.
Obviously in team sports, athletes not only have people to help them accomplish their goals, but they also have confidants to turn to in the heat of battle for advice, encouragement and respite. In individual sports such as golf and boxing, there are caddies and trainers to talk strategy with during breaks in the action.
But in singles tennis, there are no teammates to turn to and coaching is not allowed. An athlete might be able to draw some positive energy from a cheering crowd or a glance at a loved one in the stands, but for the most part, Agassi is right -- a tennis player's home is a 27-by-39-foot island, and the only person to talk to for two, three, sometimes four hours at a time is himself. Players are not even near anyone else like they are when competing in swimming or track. (And I know people who can't handle seeing a movie by themselves.)
Some say hitting a curveball is the hardest thing to do in sports. That might be true. But if a baseball player strikes out each time at the plate during the World Series, he still can win a ring and ride a float. If a tennis player is unable to return the ball, he doesn't win squat. If a golfer is in the midst of a poor round on Friday, she knows she can put that rough patch behind her and put herself into contention on Saturday. A tennis player has no tomorrow, not at that tournament, anyway.
And because matches are not timed, tennis players have no sense of how long they will have to remain sharp. Boxers know rounds are three minutes. NASCAR drivers know how long the track is. There are no such comforting measurements in tennis. In last year's Australian final, Federer and Nadal battled for four hours and 22 minutes. There is no telling how long Federer and Andy Murray will play for the title this year. That is both the beauty and agony of the sport. It's win by two, no matter how long it takes. Not many people have the mental stamina to stay in an indefinite battle.
British poet John Donne wrote, "No man is an island" because we all are connected and supposedly thrive when we interact with each other. In the world of professional tennis, that connection is minuscule. Former players such as Brian Vahaly and Justin Gimelstob have told me how covertly hostile the locker room can be. How each guy is trying to find anything to get a mental edge on his opponent, and because each guy is potentially an opponent, it's difficult to completely drop defenses -- for 11 months. So a tennis player travels the world, often alone. He hits with other players but is cautious not to show too much. And he stares down an opponent who might be 80 feet away physically but is right in his grill mentally because both understand the strain of constant isolation and each is hoping that today the other will crack before he does.
That is the solitary confinement Agassi wrote about.
That is the solitary confinement, that loneliness that separates tennis players from all other athletes and makes their sport so challenging mentally.
While taking his digs at Sampras, Agassi also mentioned how robotic and boring his rival was.
I envy Pete's dullness. I wish I could emulate his spectacular lack of inspiration, and his peculiar lack of need for inspiration ...
We've all heard similar criticisms of Sampras before, but perhaps it's misguided. Maybe Sampras appeared emotionless because he learned early on that emotional displays undermined his ability to stay mentally sharp, to stay on top.
Perhaps Sampras was showing us one is indeed a lonely number.
LZ Granderson is a senior writer for ESPN The Magazine and a regular contributor to ESPN.com. He can be reached at firstname.lastname@example.org.