Rafael Nadal paying the price of prematurely earning world No. 1

On Sunday in London, Rafael Nadal was awarded the world No. 1 trophy, an honor that now looks little more than a consolation prize.

After a gritty, painful 7-5 (5), 6-7 (4), 6-4 loss to David Goffin on Monday, Nadal announced he was pulling out of the tournament with a knee injury.

The one pressing question that loomed in the wake of Nadal's withdrawal was whether he was lured into playing too much tennis in order to secure the No. 1 ranking, something he -- and Roger Federer -- repeatedly said he would avoid.

Last month, a fatigued Federer pulled out of the Paris Masters in order to be fully fit for this event. But with the top ranking within his grasp, Nadal decided to enter Paris to secure the year-end No. 1 ranking. He did that with an opening-round win, but it came with a price. Nadal pulled out of the tournament with knee trouble before the start of his third match. The grind of the hard surface, especially this time of year, was too much.

Hard courts are also the surface of choice at the ATP Finals, an issue that has loomed large in Nadal's mind for many years. Before this event began, Nadal told Britain's Daily Mail newspaper, "I believe that it's not fair that a player like me really never played on a [year-end] surface that was a little bit more favorable [clay]. I always played on the worst surface possible for me."

Which makes his decision to enter Paris that much more questionable -- even if the year-end No. 1 ranking was at stake. In eight tries at the ATP World Tour Finals, Nadal has never won. It's the most glaring hole on his otherwise robust resume. And a tournament he no doubt wants to win.

Some tennis insiders either sympathize or agree with Nadal on the subject. After all, clay is the second most common surface on the tour, and Nadal is the acknowledged King of Clay.

"Rafa's complaint is legitimate," ESPN analyst Brad Gilbert said. "It would be awesome to put it on clay indoors, or even outdoors somewhere."

But that's problematic. In an email to ESPN.com, Pat Cash, who currently coaches CoCo Vandeweghe, wrote, "How would it be possible to have the indoor season finish in Paris -- and then follow it with a year-end championship on clay?"

That's too drastic a change in such a short period of time.

"Fair? I'm not sure that's the right word," Federer said to reporters Monday in London, referring to Nadal's complaint. Fed went on to remind us that there's no Masters 1000 on grass, and just one that is played indoors -- both surfaces on which Federer shines.

Federer is assured of a more satisfying end to the year than Nadal. He not only finished a perfect 4-0 against Nadal this season, Federer's chances of winning an unprecedented seventh World Tour Final title also improved considerably.

Federer is playing chess, not checkers. He has played a judicious schedule this season, one in which his priority has been health and fitness -- not ranking points. Notably, he bailed on two Masters events, in Cincinnati and Paris, to preserve himself for the larger payoff. He knows that bagging another year-end title would constitute the perfect conclusion to 2017.

"I had a romantic vision of these guys playing in London for No. 1," said Paul Annacone, a Tennis Channel analyst who coached Federer through some of his greatest years. "It would have been such a great ending. But Roger showed that he wasn't going to be tempted into risking his health."

A temptation that was apparently too great for Nadal.