There could be some alarming news for Rafael Nadal fans, especially as he prepares to enter the most important time of the year for him - the clay-court season, which begins next week with the Masters 1000 event in Monte Carlo.
He is scheduled to play four of the next five weeks heading into the French Open (May 23 - June 6) - in Monte Carlo, Barcelona, Rome and Madrid.
Bothered by tendinitis in both knees last year that kept him out from the French Open in June until the Rogers Cup in Montreal in August, and then by a torn ligament in his right knee during the Australian Open this year that had him off the tour for five weeks, Nadal may be suffering again.
The Spaniard lost 4-6, 6-3, 6-3 to Andy Roddick in the semi-finals of the Sony Ericsson Open last Friday. During the match, he seemed to lose some intensity from late in the second set onward. In the final game of the second set, when he hit a passing shot that went a little high and provided an appetizing volley for Roddick, Nadal did not even make a move to try to cover the American's reply.
He also looked resigned near the very end, missing a makeable backhand volley on the penultimate point and then badly over-hitting on a forehand on the only match point.
It seemed odd at the time but the following video in Spanish from the Roddick match suggests an old injury problem may have re-emerged.
During a change-over (at about the 1:20 mark on the video), Nadal can be seen angrily hitting his left knee and apparently indicating to his courtside crew that it is bothering him.
With all his injury woes, Nadal has not won a tournament since the Italian Open on red clay in Rome on May 3 of last year.
After he played impressively in reaching the semi-finals of back-to-back hard-court events in Indian Wells and Miami over the past month, it had been thought his tender knees were no longer a problem - maybe not!