He gave Tiger Woods and the rest of the field something to think about by scoring a seven under par 65.

Steve Stricker and Argentina's Angel Cabrera are only one behind and world number two Phil Mickelson, Lee Janzen and John Huston all had 67s.

But Nick Faldo, Sandy Lyle and Colin Montgomerie were all in the lake at the short 12th, the hole costing them a six, a five and a four respectively as they fell way behind.

Montgomerie had already followed a double bogey seven on the long eighth with bogeys on the next two.

Woods himself did not make his presence felt in the way he hoped at the start of his bid for an historic clean sweep of the four majors. But with a 70 he was far from out of it.

A bogey at the first, where he pushed his drive into the trees and went from there into the bunker, was an immediate blow and while he did hit back with birdies at the third, seventh and ninth to turn in 34, another bogey came on the 10th.

After failing to birdie the first three par-fives Woods did at last get one on the 500-yard 15th.

Sergio Garcia, twice winner Jose Maria Olazabal and Thomas Bjorn were in the group alongside Woods, but those ahead included defending champion Vijay Singh with a 69 and, leading the European challenge, Miguel Angel Jimenez with a 68.

DiMarco's grip has been labelled the "psycho" method. He has a standard-size putter, but spreads his hands in the manner that Bernhard Langer employs with his broomhandle.

Partnering 1988 winner Lyle, the first drama came when the third member of the group, Australian left-hander Greg Chalmers, hit a spectator on the head with his opening drive.

The man was felled and play was held up while medical attention arrived and took him away, but when it resumed DiMarco went to the turn in 32 and then coming home added further birdies on the 12th, 13th and 15th.

Lyle, playing only his third tournament of the year after losing his US Tour card, finished with 74, while Faldo managed only a three over 75, the same as Padraig Harrington.

Montgomerie, in the second last group of the day, was motoring along nicely at one under after seven, but then came a double bogey seven on the 550-yard eighth, bogeys at the next two and then his tee shot at the 12th.

It made it onto dry land, but only on the bank short of the green and after looking as if it might hang there it trickled slowly into the drink.

At least a pitch to three feet saved him from dropping any more than one shot and from four over he showed character by grabbing birdies at the 14th and 15th.

Ian Woosnam did better with a 71, while Darren Clarke posted a 72 and Paul Lawrie had 73.

Harrington had birdied the first two holes, but collapsed to an inward 40 with bogey sixes at the 13th and 15th and other dropped shots on the 14th and 17th.

The big-hitting Cabrera won his home Open last Sunday and in only his second Masters he produced a flawless round, going to the turn in 32 like DiMarco and picking up further shots at the two par-fives on the inward half.

Stricker, winner of the million-dollar first prize at the world match play championship in Australia in January, eagled the 13th and birdied the next two to burst into the picture, while Mickelson had five birdies in six holes from the 12th.

James Driscoll, last year's US Amateur runner-up, had a fairytale debut just like DiMarco. He needed only 23 putts as he shot a four-under-par 68.