Nadal had not dropped a set all week until this loss. And he has been warning the comeback might be slow, needing to regain his speed and match fitness. He has said the knee still hurts, and has warned it might be several months before it's clear if the non-surgical treatment has been effective.

The first set went to a tie-break without a service break. Zeballos kept Nadal off balance with his serve and hit the corners, but the Spaniard held on to win the tie-break. Zeballos would not be denied. He out-played Nadal in the second set, lashing surprise winners past the Spaniard to take the tiebreaker 8-6. As in the first set, there were no service breaks. After winning the set, Zeballos raised both hands at the net and stared directly at Nadal. Zeballos was broken in the first game in the final set, but broke back in the next game and then took the match, breaking Nadal again in the 10th game. Nadal's last match before this tournament was a loss last year in the second round of Wimbledon to little-known Czech player Lukas Rosol. This one was similarly surprising. They had met in the 2010 French Open with Nadal winning 6-2 6-2 6-3. Nadal has $50 million in tour earnings, and Zeballos has won only USD 1.3 million and indication of the gulf between them. The loss ended a 15-match winning string for Nadal in singles on clay. AP KHS KHS 02110942 NNNN