Rafael Nadal is injury-free, but his record this year against top players is unambiguous. PHOTOGRAPH BY DEAN MOUHTAROPOULOS / GETTY

It’s not easy—it’s wistful-making, like the first shortening days of high summer—to watch a great tennis champion begin to fade. Basketball stars and football heroes have teammates to magnify what they still have left, to mask their diminishments and even carry them, with luck, to one last big victory. Tennis players are always alone. When age and wear catch up to them, when they lose a step or a few miles per hour on their serves and forehands, and then the confidence that their speed and strength had engendered, they are isolated for scrutiny. They, of course, understand what’s going on, and try to feign or adjust, though body language and facial expressions have a way of revealing the true state of things: not the decline itself but the disappointment and, sometimes, an angry disbelief that what once was is somehow no more. Their opponents sense it, and pounce. We fans see all this, and find ourselves fidgeting before our TVs—it’s so subtly excruciating—and taking longer strolls during the commercials that come with those crossovers after every other game.

Rafael Nadal is fading. Nothing would make me happier than to be wrong about this, and his end has been declared before: in 2011, when Novak Djokovic beat him six times in six finals (Rafa came back in 2012 to take three of the four matches the two played, losing only in the Australian Open final, in five thrilling sets, perhaps the greatest match in the modern history of men’s tennis); and again in 2014, when a back injury, then a wrist injury, and then appendicitis kept him sidelined (he regained top-five form in the second half of 2015). But there are so many signs. He’s injury-free, but his record so far this year against players in the top fifty is 0-4. He is the greatest clay-court player tennis has ever seen, but over the past two years he has lost on clay five times to players ranked outside the top fifteen. (In the nine years prior to that? Three times.) In January, at the Australian Open, he lost, in the first round, to Fernando Verdasco, a player he has owned since they were teens growing up together in Spain. His A.T.P. point total for 2016—the “live” rankings, as they are known—puts him at No. 21, just behind the eighteen-year-old American sensation Taylor Fritz.

What afflicts Nadal? Tennis is a game where the barely noticeable makes all the difference. Nadal’s serve has never been his strength, but it has grown weaker, and the percentage of service points he has been winning lately, 63.5, is down about four per cent from his average over the past few years—and is significantly lower than that of most other top players. I haven’t watched every match he’s played this winter, but I have noticed that, at times, he’s stepping inside the baseline early in rallies, trying, it would seem, to shorten points; this taking the ball early, on the rise, can throw off the timing of his mighty forehand and result in his pushing the ball back, leaving it short for his opponent to attack. And he is losing tight matches when he has had a lead or a chance to win—failing to “close,” a problem Rafa has never had. In Buenos Aires last month, on clay, he was up 5-4 in the third set against Dominic Thiem, a young and rising Austrian player, and had a match point, but failed to convert. Nadal eventually lost in a third-set tiebreak. Thiem, it’s worth mentioning, is a righty with a one-handed backhand. With that lefty forehand of his, Rafa—as Roger Federer spent years being reminded—did not lose to righty one-handers on clay. But he does now. Another sign.

And then there is this not-so-little thing: Nadal will turn thirty, in June. Thirty may be the new twenty-four on the men’s tour, but not if you turned pro at fifteen, as Rafa did, and especially not if you play the kind of tennis he does. Numerous coaches have said quietly for years that Nadal’s coarse groundstroke technique and the grinding, all-out nature of his game—long, long rallies, chasing every ball as if it were championship point—would soon enough break down his muscled-up body. “Soon enough” didn’t arrive all that soon, but it looks to be arriving now.

Brad Gilbert, the former player and coach and now a voluble ESPN tennis commentator, remarked recently on Twitter that what Nadal needs is to bring a “new voice” onto his coaching team. Gilbert, in truth, has been making this point for a couple of years, as has John McEnroe. The thinking goes that Nadal needs to alter his approach, and that his coach, his uncle Toni Nadal—who introduced Rafa to tennis when he was three years old and has been at his side on the practice court ever since—can’t see that, never mind help Rafa accomplish it. Last fall, Toni told Agence France-Presse that he was open to bringing on a “super-coach,” i.e., a former tennis great, the way that Djokovic brought on Boris Becker and Federer hired Stefan Edberg to fine-tune (Djokovic) or change up (Fed) their games. But what’s left for Rafa to do? Come to the net more, like Roger? Could Rafa ever play a game that doesn’t revolve around controlling a point, or trying to—scrambling, darting, hustling—until he has a forehand (just to the right of midcourt, preferably, and a little short) that he can drive inside out or inside in with laser accuracy and nearly unimaginable pace and topspin? Vamos!

The BNP Paribas Open, in Indian Wells, California, begins today. I’m heading there next week, and I hope Rafa gets through the early rounds and is still in the mix. I’ll watch his matches if so, if only for flashes of what once was. Tennis fans will miss him—that friendly ferocity, the sweaty belief that each point is an opportunity for greatness, even transcendence. I miss him already.