Mark Wilson leads with opening 64 - Chrysler Classic of Tucson 2006

The 31-year-old from Illinois, whose best PGA Tour finish was a share of third at last year's Texas Open, completed an eight-under-par 64 at the Tucson National Golf Resort and Spa.

After teeing off at the par-five 10th, Wilson reached the turn in two under before holing a 30-foot eagle putt at the par-five second.

He picked up further shots at the fourth, fifth, seventh and ninth for a blistering second nine of six-under 30.

"It was a story of two nines today," Wilson told reporters.

"If I could have rolled in a few birdie putts early on and not made a silly bogey on 18, the round could have been something real special. But I'm still very happy with how it was."

Former winner Gabriel Hjertstedt of Sweden was among a group of five tied for second place after collecting five birdies in an error-free round.

Level with Hjertstedt, the 1999 champion, were Americans Duffy Waldorf, Jerry Kelly, John Riegger and Doug Barron.

Germany's Alex Cejka birdied the last two holes for a 67 to end up in an 11-way tie for seventh, along with big-hitting Americans Bubba Watson and Ricky Barnes, and Paraguay's Carlos Franco.

Former world number one Nick Price, making his first PGA Tour appearance of the year, opened with a 72, as did French Ryder Cup player Thomas Levet.

Britain's Justin Rose, playing his fifth U.S. event of the season, carded a 70 and South Africa's Trevor Immelman returned a 68.

With the game's leading 64 players competing in this week's WGC-Accenture Match Play Championship at La Costa Resort and Spa in Carlsbad, California, Wilson and company have a freer hand in Tucson.

Eight of the last nine winners are playing this week, including Jeff Sluman (1997), David Duval (1998), Hjertstedt, Canada's Ian Leggatt (2002) and 2004 champion Heath Slocum. (Writing by Mark Lamport-Stokes in Carlsbad, California)