* Piercy hammers world number three Donald 7&6
* Poulter and defending champion Mahan both advance
* Colsaerts wins 4&2 against Rose (Updates at end of second round)
By Mark Lamport-Stokes
MARANA, Arizona, Feb 22 (Reuters) - Former champion Luke Donald was the biggest name to fall in the second round of the snow-delayed WGC-Accenture Match Play Championship after being pummelled 7&6 by American Scott Piercy on Friday.
The British world number three was totally outplayed by Piercy, who was effectively seven-under par on his ball after being conceded a four-foot birdie putt at the short 12th to seal the win.
Piercy spectacularly holed out with a four-iron from 221 yards to eagle the par-four fifth, then birdied the sixth, eighth and ninth to go 6up on Donald by the turn on a sunny but cool and breezy day at Dove Mountain.
"Scott played very well, I played just very average," 2011 Match Play champion Donald told reporters. "I probably didn't drive it well enough today to put any pressure on Scott.
"He was just playing extremely solid, didn't give me really a look. I had a few opportunities on the greens, but for whatever reason I was just not making the putts today, and hence I'm going home."
Making his first appearance in the elite World Golf Championships (WGC) event, Piercy will next meet 2001 champion Steve Stricker who edged past fellow American Nick Watney after 21 holes.
"I played really solid today," said double PGA Tour champion Piercy, whose 7&6 margin of victory has been eclipsed only five times at this event.
"I hit every green in regulation. I got up early and tried to lean on him once I got up. It was just a solid day all around.
"I think he was off a little bit," the American said of Donald who double-bogeyed the opening hole. "From the first tee shot it didn't look like Luke. I just tried to make some birdies and stay out ahead of him."
The stunning departure of Donald follows the premature exits on Thursday of world number one Rory McIlroy and three-times champion Tiger Woods.
Northern Irish McIlroy, a losing finalist last year, was eliminated 1up by Ireland's Shane Lowry and Woods was eliminated 2&1 by fellow American Charles Howell III.
World number 68 Lowry continued his winning form on Friday, making five birdies in a flawless display on the way to a commanding 6&5 victory over Swede Carl Pettersson.
Howell, however, ran out of steam as he was crushed 6&5 by Spaniard Gonzalo Fernandez-Castano.
Long-hitting Belgian Nicolas Colsaerts became the first player to reach the third round with a 4&2 upset win over British world number six Justin Rose on Friday.
Nicknamed the 'Belgian Bomber' because of his power hitting, Colsaerts will next face American Matt Kuchar, who beat Spaniard Sergio Garcia 2&1 in a closely contested match between two Ryder Cup players.
Ian Poulter, the 2010 champion, also advanced with a 3&1 victory over American Bo Van Pelt to set up a third-round encounter with South African Tim Clark, who beat Dane Thorbjorn Olesen 3&2.
"I had seven birdies, no bogeys, and when you play like that, and you don't give your opponent anything, then obviously it's going to be a tough day for him," matchplay specialist Poulter said with a smile.
Defending champion Hunter Mahan never trailed on the way to a commanding 4&3 win against South African Richard Sterne and he will take on Germany's Martin Kaymer in the next round.
Kaymer, who lost 3&2 to Donald in the 2011 Match Play Championship final, advanced by beating Spaniard Rafael Cabrera-Bello 2&1.
"I just feel comfortable here ... from the tees to the greens and everything," said Mahan. "I feel like I just know where I need to hit it.
"Confidence is high. I know I can play this place well, and I know I can beat anybody on any given day."
In other second-round matches, Masters champion Bubba Watson battled past fellow American Jim Furyk after 22 holes and U.S. Open winner Webb Simpson beat Swede Peter Hanson 1up after never leading until the 18th.
With the snow-delayed first round finally completed earlier on Friday, officials plan to get the tournament back on track with the third round and quarter-finals both set for Saturday. (Reporting by Mark Lamport-Stokes; Editing by Steve Keating/Gene Cherry)