It was my first-ever competitive round, I think, without having any nicotine in my body Darren Clarke

Clarke, who has given up beer and smoking since joining the 2004 PGA Tour, shot a 67 in Hawaii to lie one shot behind leader Stuart Appleby.

Clarke, who has lost 30 pounds, is a shot clear of Kirk Triplett, Scott Hoch, Justin Leonard and Vijay Singh.

World number one Tiger Woods eagled the last hole to finish with a 71.

European Order of Merit winner Ernie Els began the season-opener at Kapalua with a level round of 73.

The South African set a PGA Tour scoring record of 31-under-par in winning this event last year.

Clarke, who arrived in Hawaii last Friday to acclimatise, decided at the end of last year that he needed to lose weight in order to compete.

Clarke before he started his new health regime

"I think the way I played towards the end of November, start of December, you couldn't really describe that as playing" he said.

The Ulsterman has been working diligently with the help of a trainer - and with the encouragement of fitness fanatic Woods.

And for the final sacrifice, he has given up beer and smoking.

"From New Year's Day, I decided to try and give up [smoking]. I have managed it so far. I will keep on trying to stay off them."

"It was my first-ever competitive round, I think, without having any nicotine in my body.

"No beer, no nicotine. Don't know what's going on really," Clarke said.

Woods, who missed last year's event while recovering from knee surgery, made up for an otherwise disappointing day at the last.

"I either hit great or horrific shots," Woods said. "It was not a relaxing round, [but] I ended up on a good note."