On Tennis: Rafael Nadal, King of Clay, is slipping

I always get a tinge of sadness watching a battle-scarred lion being forced out as king of his pride. I'm not really sure why. After all, he had a great run, perennially vanquished his foes, and enjoyed the spoils of victory. Maybe it's just a reminder of the brevity of life, the ephemeral nature of strength and success.

Whatever the reason, I'm having the same feeling watching the King of Clay, Rafael Nadal, as he girds his loins to defend his own domain at this year's French Open.

Ever since winning his record ninth title in Paris last year, Nadal has been struggling. He was out with yet another injury for much of the second half of 2014 but this time did not return with supremacy as he has after previous setbacks. He has suffered eyebrow-raising defeats in the early rounds of tournaments. This spring in the European clay court events leading up to Roland Garros, where he used to gobble up titles like tasty tapas at a Spanish sidewalk cafe, he has hoisted nary a one. He is the five-time defending champion in Paris but this year is seeded only sixth.

He said recently, "If I go to Roland Garros [and] I lose [and] I don't play well, life continues. It's not the end of the world. I won so many times there. I don't want to [win] 15 Roland Garros. That's for sure. It's normal that I can lose. Losing is part of life." And then he added: "I am sure that I can be competitive."

Competitive? Nadal has never been competitive in Paris. He's been dominating, leaving everyone else with a highest hope of second place. Something is not right with him. He knows it, and so does everyone else.

But what exactly is "it"? Is he still nursing an injury? Is his intimidating physicality on the wane as he nears 29? Is doubt, pressure, expectations, or perhaps a personal problem cluttering his mind?

It could be one, some, or all of the above. Nadal himself may not even know. Such is the razor-thin margin at the upper echelon of the game, where the slightest, even imperceptible, drop in anything results in an uncharacteristic unforced error on a big point or a once-infallible forehand missing by an inch instead of cleaning the line.

Even though his longtime rival, Federer, stands at world No. 2, the Swiss is not the lion most likely to oust Nadal from the pride. That would be world No. 1 Novak Djokovic, who has won all but two matches this year, including the Australian Open and four other titles. Yes, the Serb has come up short all six times he has faced Nadal in Paris, but their diverging arcs over the past year strongly suggest that a potential seventh duel in the quarterfinals this year could net a different result.

Djokovic is a highly efficient player with clean strokes, deft movement and a ruthless mind. Unlike other greats who possessed weapons that elicited oohs and ahhs, the Serb's strength is his solidity in every aspect of the game. In fact, he's steamrolling the entire tour so much right now that if he wins the French Open, the one major he's lacking, a calendar-year Grand Slam will become very much in view.

The same can be said for women's world No. 1 Serena Williams. Like Djokovic, she has dominated this year, losing only once, and unlike Nadal, she shows no sign of giving ground at age 33. And yet the slower courts of Roland Garros absorb enough of her power that she has won only two of her 19 major titles in Paris. In the coming fortnight, her own dreams of a calendar-year Grand Slam will live on or die on the terre battue.

Paris will indeed be pivotal. Rare feats are at stake. There are no foregone conclusions this year. The King of the Clay Court Jungle is in grave danger of being ousted from his reign. But it will take a monumental effort from a challenger, especially in a three-of-five-set duel. And let's not forget, a wounded lion can be the most dangerous.