Duval has endured a miserable last few years

Duval, the former world number one and Open champion, has made the cut at a PGA event just once in 2005.

But the 34-year-old reeled off four successive birdies in one of his best tournament rounds in years.

Colin Montgomerie shot a one-over-par 71 while New Zealand's US Open champion Michael Campbell was two over.

Duval said: "I'm very aware of how I've played over the last few years. It's nice to start a tournament well."

But Duval admitted that his strong performance on Thursday could not disguise his long-term problems.

It's been tough for all of us to watch Tiger Woods on David Duval

"My physical condition is incredibly mediocre," he said, citing back, foot and hand pain that has kept him from training for two years.

Current world number one Woods, who has earned more than �6m on the PGA tour this year, was happy with his five-under-par round, which included just one bogey at the second hole.

Woods also had words of sympathy for his former World Cup partner Duval.

"It's been tough for all of us to watch," he said. "But he's coming back to a place where he won before and that always helps."

American Jim Furyk and Japanese pros Shinichi Yokota and Tomohiro Kondo were two shots back at 67 in the tournament, Japan's richest.