Dirk Nowitzki started to grab the part of his left leg that hurt the most, then stopped. He might not have known what to rub first. So the reigning league MVP dejectedly put a hand on his head. Then pounded the court. Nowitzki was injured on an ugly looking fall in the third quarter of Dallas' 88-81 loss to the San Antonio Spurs on Sunday, but left the arena without knowing how bad it is.