Rafael Nadal had his serve broken four times by one of his former ball boys before progressing to the second round of the China Open.
The world number eight beat China’s 230th-ranked Wu Di 6-4 6-4 in his first match since being knocked out in the third round of the US Open last month.
Top seed Novak Djokovic extended his perfect record in Beijing to 25-0 by beating Simone Bolelli 6-1 6-1. His winning run began in 2009, when he won the first of five China titles.
Nadal dropped three straight games on his serve in the second set against the wildcard. He will play Canada's Vasek Pospisil in the second round, while Djokovic faces John Millman.
In the women's event, Flavia Pennetta of Italy advanced to the third round with a 3-6 6-0 6-4 win over Brazilian Teliana Pereira. Ana Ivanovic beat Venus Williams 7-6 (7-3) 6-2, and Caroline Wozniacki defeated wildcard Wang Qiang 7-5 6-0