Where does Rafael Nadal go from here?

The rumors began just hours after Rafael Nadal lost in the second round at Wimbledon to the No. 100 player in the world, Czech Lukas Rosol. By the time the week was out, Nadal watchers in the Spanish press and tennis establishment had pretty much given up hope that Nadal would be able to successfully defend the gold medal he earned at the Beijing Olympics.

This had nothing to do with Rosol's well-earned upset. He simply blasted Nadal off the court. But the truly bad news for Nadal was that he was again undergoing MRI evaluations and receiving treatments for his chronic tendinitis, even before he left London.

Yet even the most pessimistic observers thought that Nadal would at least participate in the Games. After all, he was not only defending champion; the 26-year-old, 11-time Grand Slam champion had been chosen by his nation's Olympic committee to carry the Spanish flag in the opening ceremonies. It's the highest of honors for an Olympic athlete.

We learned Thursday that Nadal will neither carry the flag nor compete in the Olympics because of the tendinitis in his knees, particularly the left one. According to the Associated Press, Nadal said of his withdrawal, "It's one of the saddest days of my career as one of my biggest ambitions, that of being Spain's flag bearer in the opening ceremony of the Games in London, cannot be."

His coach and uncle, Toni Nadal, told IB3 TV in Spain: "Rafael has gone through bad times and serious injury, but I think this is the worst moment of all."

This marks the second time that Nadal has missed a huge opportunity in tennis because of his stressed and increasingly faulty hinges. In 2009, he was unable to defend the Wimbledon title he had taken from Roger Federer. That famous final one year earlier helped propel Nadal past Federer as the top-ranked player in the world.

This injury also raises the question of just how fit Nadal will be in the second half of the year, which has never been his most productive period.

Nadal has fallen to No. 3 on the heels of Federer's recent triumph at Wimbledon, a win that enabled him to wrench the No. 1 ranking from Novak Djokovic. Given that the U.S. Open has been the most challenging Grand Slam event for Nadal, and that the fall has traditionally been the season of his discontent (with those knees, you can understand why), the Olympics seemed like his last best chance to record a big win somewhere other than at Roland Garros this year.

Now you have to wonder if the Nadal juggernaut, re-fired in the course of his outstanding spring, hasn't come to a grinding halt again. Shoot the messenger if you wish, but I'll put it bluntly: Nadal isn't getting any younger, and his knees aren't getting any healthier. Add the discontents Nadal has been expressing for about 18 months now about the tour and its demands and you have to wonder where he goes from here.

But there's another factor to consider here, which is that at the time of the cutoff for direct entry into the Olympics, Spain had five men in the ATP top 20. The cutoff for direct acceptance was No. 56, but the Olympics embraced a rule stipulated that no more than four players from any nation would be accepted directly into the draw.

Thus, world No. 17 Feliciano Lopez was left out in the cold, while some players ranked 40, 50 places (or more) below him were in -- either through direct entry or via special exemptions. Given that Nadal was under doctor's orders to rest his knees, it seems natural that interested parties from the Spanish federation and Lopez on up to Nadal himself had to think long and hard about what to do. Would it be fair for Nadal to take up a place in the draw under the circumstances?

Nadal himself answered the question Thursday when he also said, "I have to think about my companions; I can't be selfish and I have to think of what's best for Spanish sport."

Granted, Lopez has slumped terribly since the cutoff rankings of June 11. He won just one match between the start of the Madrid Masters and the end of Wimbledon and has dropped to No. 30. But he's a dangerous left-hander who likes to attack and volley -- not a bad recipe for success on the grass courts of Wimbledon, where the Olympic tennis event will be held.

It wasn't the worst of times for Nadal to take a bullet for the team, but that doesn't mean his knee problems are any less serious, or that they haven't brought his career to a tipping point.