Rafael Nadal started the week by laying claim to the No. 1 ranking for the end of the season in the ATP. But he didn't end the week on the Tennis court. The Spaniard was forced to withdraw from the Paris Masters on Friday (Nov. 3) after suffering a right knee injury. The injury occurred during the tournament, though it was something it seemed like he would be able to work through for the remainder of the week. Instead, his participation in the year's highly-hyped year-end tournament has suddenly come to an end.

Paris Masters loses their star

The inklings of a problem began to appear during the third-round of the Paris Masters.

During a match against Pablo Cuevas, Nadal needed to have his right knee taped. Nevertheless, he gritted his way through the victory. It was clear to everyone watching that he wasn't moving as fluidly as he was before and was slowly losing his ability to even raise up his legs. He would end up double-faulting near the end of the match.

A report by ESPN states that after pulling out of his match with qualifier Filip Krajinovic, Nadal expressed disappointment about needing to pull out of the Paris Masters. He was especially disappointed due to the special bond he holds with the city of Paris. He claimed to have received treatment over the previous few hours, but that it wasn't enough to get him over the hump.

He may have claimed the year-end top ranking at the beginning of the week, but he was walking away with additional questions at the end of the week.

Projecting Nadal's absence

Knee injuries are not a new issue that suddenly cropped up for the first time at the Paris Masters. He has missed extended time in the past due to knee injuries, in addition to a significant wrist injury.

Nadal figured there was no point in continuing on when there is a more important tournament for the ATP on the horizon.

The ATP Finals begin on November 12 and early indications about Nadal's status for the tournament are vague. The tennis star will be consulting with a doctor to determine the seriousness of the right knee injury.

He appeared to be optimistic due to the success of treatment in the past, specifically referencing his recovery after having some woes during the Shanghai stop of the tour.

If Nadal is unable to go at the ATP Finals, however, it will cause a steep decline in interest for the tournament. It will also start questions as to Nadal's availability for the Australian Open, as well as whether or not retirement could be in the near future.