Tomas Berdych of the Czech Republic quashed a spirited challenge from Frenchman Benoit Paire to clear the first hurdle at the Japan Open tennis tournament on Monday.
The 2008 champion, fresh from reaching the semi-finals at the US Open last month, got off to a flying start before ending up with a 6-1, 7-6 (8/6) victory in 104 minutes.
"I thought the match might be tough since the beginning, so I was a bit surprised how I won the first set. But it was going to be even a bigger fight. He made me fight hard in the second set," said the second seed.
Berdych added he was not in his peak physical condition due to jet lag.
"It was very tough to stay focused on each point. When I was 5-4 up (in the second set), I lost my serve, got into the tie-break, facing a set point down. It was a very close one in the end. I'm happy to take it on my serve," he said.
In the second round, Berdych will play either Thomaz Bellucci of Brazil or Alejandro Falla of Colombia.
In other action, Beijing Olympic doubles gold medallist Stanislas Wawrinka of Switzerland, seventh seed, defeated Japan's Hiroki Moriya 7-5, 4-6, 6-4, while Lukas Lacko of Slovakia eased aside Albert Ramos of Spain 6-0, 6-2.