* In-form Australian storms clear at Royal Melbourne
* Former world number one Singh tied for second
* American world number eight Kuchar five strokes behind Scott (Adds details, quotes)
By Ian Ransom
MELBOURNE, Nov 16 (Reuters) - Defending champion Adam Scott laid one hand on a second successive Australian Masters trophy on Saturday, shooting a five-under 66 to take a commanding four-stroke lead into the final round.
Joint leader with compatriot Nathan Holman overnight, the U.S. Masters champion rolled in seven birdies on another breezy day at Royal Melbourne for a 14-under total of 199, well clear of a four-player group that includes former world number one Vijay Singh.
World number eight Matt Kuchar, warming up for his World Cup title defence with the United States next week, was a further stroke adrift after carding a solid four-under 67.
Scott will be paired up with triple major champion Singh after the Fijian tore up the famed sandbelt course with an eight-under 63 to continue his late-year resurgence after a troubled season marred by a doping controversy.
With his driving and iron-play in superb touch, the world number two Australian will be difficult to catch, however.
"I just hit my shots today... hit lovely approach shots, made a couple of putts for the first time this week," Scott told reporters.
"If there's enough holes with that quality of golf tomorrow, a good score's going to be out there for me.
"Vijay must have done something like that today."
Scott's putter ran hot midway through his front nine as he drained four birdies in five holes, including three in a row from the par-four seventh to charge clear of the chasing pack.
The 33-year-old wobbled with bogeys on 10 and 11 to slip back to a two-stroke lead but recovered with birdies on 15 and 17 to march to the brink of his second successive title Down Under, having won the national PGA Championship in the Gold Coast on Sunday.
Having started with a scratchy first round of 72, Singh shook out the rust with a second round 68 before shifting into overdrive on Saturday to post the tournament's best round.
The 50-year-old hit all 18 greens in regulation and notched seven birdies and an eagle on the par-five 15th to give himself a chance.
Now eligible for the PGA Champions Tour, the big Fijian has not had a win in five years but proved he was far from a spent force with a runner-up finish at the U.S. tour's season-opening Frys.com tournament last month.
"A couple of weeks ago I was in contention so it's a good feeling," he told reporters. "It gets your blood flowing again and, you know, thank God it's a little warmer (here).
"The first two days were pretty miserable but I play better when it's warm so hopefully tomorrow is going to be a warm day and I can do what I did today."
Singh, tied on a 10-under total of 203 with a trio of local players in Holman, Nick Cullen and Matt Griffin, is likely to get his wish with the weather forecast to be a sunny and pleasant 22 degrees Celsius.
A team mate of Singh's in Presidents Cup campaigns, Scott poked gentle fun at the Fijian after he said he was hoping to avoid playing on the PGA's Champions Tour if he could help it.
"It's been a while since Veej and I played together. I don't see him that much any more now that he's a senior tour player," Scott quipped.
Scott remains on track to complete a sweep of Australia's three marquee tournaments with the national Open to come in Sydney. (Editing by John O'Brien)