Top seed Kei Nishikori recovered from a nervy start to beat American Donald Young 4-6, 6-2, 6-2 in his opening match at the Japan Open on Monday.
The Japanese world number five, who reached the semi-finals of last month’s US Open, looked horribly out of sorts against a player who only got the call to play in Tokyo after Spain’s Nicolas Almagro withdrew with illness.
“I wasn’t being aggressive enough in that first set and was missing a lot,” Nishikori told reporters.
“He was coming into the net a lot but he slowed down in the second set and I began to find my range.”
Nishikori, who won the Japan Open in 2012 and 2014, is favourite to win a third Tokyo title after US Open winner and defending champion Stan Wawrinka pulled out with a back injury.
Earlier on Monday, fourth seed Marin Cilic also made hard work of his opener before seeing off Frenchman Benoit Paire 6-0, 4-6, 6-3.
In other matches, Portugal’s Joao Sousa beat Martin Klizan of Slovakia 4-6, 6-3, 6-3 while Spain’s Fernando Verdasco edged Japanese veteran Go Soeda 6-7, 6-3, 6-3.