An 80-year-old putter purloined from an American student at St Andrews threatens to thwart Darren Clarke's charge towards a first Order of Merit and victory in the Turespana Masters this week.

In the hands of the Zimbabwean Tony Johnstone, who acquired the rusty relic during last week's Dunhill Cup, it became a magic wand at the Club de Campo yesterday, propelling the former PGA Champion to an opening 66.

"I am like Lawrence of Arabia in sand, but I can't read lines or slopes, and it's the first time I have putted well for four years," he said.

Six birdies swept Johnstone alongside the Irishman and defending champion Miguel Angel Jimenez, two ahead of Sergio Garcia, who shot an unblemished 68.

Clarke was home in 31 for a round of 66 in his quest for the £98,000 sterling first prize that will enable him to leapfrog the European Tour leader Lee Westwood.

Clarke had three birdies and two bogeys on the front nine, but picked up four shots on the back nine, wedging 130 yards from a fairway bunker to 15 feet and holing for a birdie at the 18th.

"I struggled a bit at the start, but then hit a lot of nice shots and putted well for the first time in a long time," Clarke said. "Obviously, the money-list is my prime goal."

"I felt really good before I went out, but when I started I was not quite right and pulled a couple of shots." Local favourite Santiago Luna (65) and Austrian rookie Markus Brier, who had only 23 putts in his 64, lead the field into today's second stage.

Brier, the only Austrian player to secure a European Tour card, sank no putt shorter than eight feet and rolled in his seventh and final birdie from 35 feet at the 18th.

"I just holed everything today," Brier said. "That's my lowest round on Tour. When I got to the course I thought how much it looked like Catalunya where I was second," he added. "So I came into the tournament with a good attitude.

"Then today I changed my routine on the greens, just relaxing instead of trying to pick out lines to a millimetre and rolling the ball with a nice easy stroke. It was a hot putter but a very relaxed one."

Two late three-putts cost Paul McGinley a share of the lead.

McGinley carded a four-underpar 67 to trail Brier by three shots, but after reaching five-under with six to play he was disappointed not to have finished the job off better.

McGinley grabbed birdies at the second and third to reach five under par. But he came unstuck by running up a six on the long fourth and dropped another shot two holes later to be only three under again.

The 33-year-old Dubliner has not won on the European Tour for four years, although seven top-10 cheques this year have taken him to 19th on the Order of Merit and in sight of securing a place in the American Express World Championship at Valderrama in just three weeks' time.

Former European number one Ronan Rafferty, who since returning from a career-threatening thumb injury has made only one halfway cut in 14 starts this season, crashed to a closing triple-bogey seven and a seven-over 78.

Over the green in two he chipped into a bunker, came out far too strong, then nearly went back into the sand.