Even the most stalwart cliche avoiders have accepted reality and taken to calling Rafael Nadal the king of clay. But sometimes you have to wonder whether "prisoner of clay" would be just as appropriate a handle.

Nadal's persistent knee problems, one of which kept him out for seven months ending just this week, are forcing him to re-examine almost every aspect of his professional life, from his priorities to his schedule to his practice routine. And the longer he looks at those things, the more sense it must seem to make for him to focus his efforts on the clay-court tournaments.

That much became apparent when Nadal, afflicted with a stomach bug, pulled the plug on a projected comeback at the beginning of the year. Instead of playing a warm-up event in Doha and getting right back into the thick of it at the first Grand Slam event of the year (the Australian Open), he pushed back his return date to this week and played his first singles match since losing to Lukas Rosol in the second round of Wimbledon at the Chile Open, in Vina del Mar.

While Chile's City of Gardens is a lovely, wealthy seaside community, the tournament there is an ATP 250, the lowest of the main tour events. Nadal's schedule then calls for him to continue what might be called his final stage of rehab in another 250 (Sao Paulo) and an ATP 500 event in Acapulco. The three things these events have in common are that they attract Grand Slam champions only if they throw enormous amounts of money at them (and that alone isn't enough anymore), Nadal has never bothered to enter any of them before, and -- last but not least -- all of them are on red clay.

Nadal is a superstitious young man. In fact, some of his habits that we see on court appear almost obsessive-compulsive. So when you take into account his well-publicized (and well-founded) fears about his future, as well as his remarkable track record on clay, the surface most friendly to knees and joints, you can see why he altered his plans and put off his return to tennis for an extra month.

The question is, is Rafa likely to become a prisoner of his own devise, in a fortress made of red clay?

Really, there are two related issues in play here. First, will he be able to play and compete comfortably and successfully on hard surfaces, including those at the Australian and U.S. Open tournaments? Second, will he want to pursue every Grand Slam title, and the top ranking, thereby accepting the built-in risk to his knees?

The first question won't be answered until it comes time for Rafa to commit to (or decide to forgo) either or both of the hard court Masters events in the U.S. (Indian Wells and Miami, which run from mid-March into early April). That will give us an inkling, although the real test of his knees on hard surfaces will start with the U.S. hard-court swing.

But keep in mind that should Rafa experience pain and tenderness through his upcoming clay-court events, he might decide to play it safe and skip the hard-court events altogether. The prognosis for full participation isn't particularly encouraging. Nadal said after his debut in Vina del Mar (it was a low-stress doubles match): "My knee keeps hurting. But the fact I am playing here is a thing of joy."

The second factor is intriguing, in that even before he left the game in July, Nadal showed streaks of disillusion with the demands of his profession. He complained, among other things, about the punishment doled out by hard-court tennis and a ranking system that was as much a treadmill as an indicator of a player's talents.

Unless Nadal's knees get noticeably stronger from the stress and strain of competition, they're likely to provide a powerful incentive for him to slash most non-clay tournaments from his schedule. (He certainly would keep the grass courts of Wimbledon on his docket.) But it would be extremely difficult for Nadal to make a serious run at the No. 1 ranking again if he skipped all or even most hard-court events.

In the past, Nadal has made it clear that he's all-in when it comes to competing for the top honors. But that would be very hard to do if he chooses to isolate himself in a castle -- or prison -- made of clay.