CINCINNATI (Reuters):

World number two Rafael Nadal withdrew from the Cincinnati Masters on Wednesday while fourth seed Novak Djokovic was upset 6-4, 6-1 by Spaniard Carlos Moya.

Nadal quit when trailing Argentine Juan Monaco 7-6, 4-1 in their second-round match, citing cramp in his left forearm and dizziness.

"I have some cramping," Nadal told reporters.

"I wasn't grasping the racket very well and I wasn't feeling very well when I went to the court. I couldn't play more than three balls on every point. I wasn't feeling well. I didn't have power in the legs."

World number 25 Monaco now plays American Sam Querrey, who upset 13th seed Mikhail Youzhny of Russia 5-7, 6-3, 6-4.

Djokovic, who beat Andy Roddick, Nadal and world number one Roger Federer to win the Montreal Masters last weekend, was brought back to earth with a bump by former world number one Moya.

Moya broke once to win the first set. Serb Djokovic had a break point in the opening game of the second set but Moya saved it and broke three times to clinch victory and set up a clash with Argentina's Juan Martin Del Potro.