LARRY NELSON began his final full season on the US PGA Tour with a seven under par 65 yesterday to take a one stroke lead after the first round of the $1.25 million Tucson Open. Nelson, 48, plans to join the Senior PGA circuit when he becomes eligible in September of next year.

Yesterday, he was pleased about sinking eight birdies at Tucson National, one of two courses used for this first full field event of the season. A birdie on the final hole pushed him a stroke ahead of rookie Tim Herron and Dillard Pruitt in quest of the $225,000 top prize.

"I'm really doing a lot of work to make this year a great year," said Nelson, who has not won since the 1988 Atlanta Classic. "I wanted to get back to the potential I knew I had. I think I'm more prepared to play now than I was 10 years ago. I made a lot of good pulls today and it's nice to start the year off without a five," he added.

Tucson National proved more forgiving than the par 71 Starr National Golf Club. Joel Edwards had the best round there with a tour under 67. Phil Mickelson, the defending champion, shot a two under 69 at Starr.