KAPALUA, Hawaii (Reuters) - Canadian Mike Weir, making the most of calmer weather, holed an 18-foot birdie putt at the last to move one shot clear in the Mercedes-Benz Championship second round on Friday.
Three off the pace at the start of the day, Weir fired a blemish-free six-under-par 67 to take control at the halfway point of the 2008 PGA Tour's opening event.
The former Masters champion rattled up four birdies and an eagle at the par-five ninth for an eight-under total of 138 on the hilly Plantation Course at the Kapalua Resort.
Compatriot Stephen Ames also birdied the final hole, ramming in a 23-footer for a matching 67, to share second place with American Jonathan Byrd (69).
Brandt Snedeker, who held the outright lead for much of the day, had to settle for a tie for fourth at six under after three-putting from 17 feet to bogey the last.
Snedeker, the 2007 PGA Tour rookie of the year, returned a 69 to finish level with overnight leader Nick Watney (72).
Weir, who qualified for the winners-only event with victory at the Arizona Open last October, took advantage of improving weather at Kapalua after a blustery and wet opening round.
"The winds weren't as strong and that makes all the difference in the world out here," the 2003 Masters champion told reporters.
"The course is still a little damp but early on the front nine, with the sun out, it was drying out a little bit and did play easier today."
Weir, who rolled in a 13-foot putt at the ninth to record the first eagle on the 2008 PGA Tour, has been delighted with his all-round play in the first two rounds.
He spent much of last year changing his swing with a new coach and reaped the benefits with his eighth PGA Tour victory three months ago.
"Obviously it's a game of a lifetime and you're always going to be tinkering with your swing," the 37-year-old said.
"But the changes feel comfortable now and I don't have to think too much. For the most part, I'm pretty happy this week. It's been pretty good for the first tournament out."
Snedeker, three off the pace overnight, pulled ahead of the field with a sizzling outward nine of five-under 31.
With his approach play in sparkling order, he reeled off three consecutive birdies from the fourth before picking up further shots at the eight and ninth.
A superb approach to five feet at the 10th and a tap-in birdie putt put him two strokes in front before he slid backwards with bogeys at the 11th and 13th.
"I played really good but missed a short putt on 11 and it wasn't the same after that," Snedeker said after offsetting a birdie on 14 with his bogey at the last. "I didn't make any putts coming in, which is very unlike me.
"Hopefully we'll get it squared away on the putting green and get ready for the weekend."
Among the big names in the field, defending champion Vijay Singh carded a 70 to lie six strokes off the pace, level with world number three Jim Furyk (70).
Writing by Mark Lamport-Stokes in Los Angeles; Editing by Greg Stutchbury