Dustin Johnson and Paul Goydos set for final-round showdown

DEFENDING champion Dustin Johnson dismissed all challengers barring fellow American Paul Goydos, who doggedly clung to a share of the lead after the third round of the Pebble Beach National Pro-Am on Saturday.

Johnson, part of a six-way tie for the lead overnight, fired an eight-under par 64 on the Spyglass Hill course, but the effort was matched by Goydos on the Pebble Beach Golf Links.

Both players moved to an 18-under total of 196 to charge four strokes clear of fellow overnight leaders, Americans Bryce Molder and J B Holmes, and Matt Jones of Australia.

Johnson, who has led or held a share of the lead over the course of the tournament, blitzed the front nine of Spyglass Hill, considered the hardest of the three courses at the Pro-Am, to match Phil Mickelson's mark of 30 set in 2005.

The big-hitting American, who also charged out of the blocks with a front nine 30 at Pebble Beach in the first round, drained a 20-foot putt to eagle the par-5 first hole after reaching the green in two.

He then notched four birdies in five holes from the third before stumbling with a bogey at the 10th.

He recovered with an eagle on the next hole and a chip-in for birdie on the par-five 14th, but dashed his hopes of equalling the 62 course record shared by England's Luke Donald and Mickelson with a bogey on the last.

While Johnson was all fireworks, Goydos was all control, turning in a bogey-free round highlighted by an eagle on the par-five second where he holed an eight-foot putt after reaching the green in two.

Both Goydos and Johnson are seeking their third tour win. The 45-year-old Goydos, named an assistant captain for the 2010 Ryder Cup, waited 11 years for his second in 2007 at the Sony Open after clinching the Bay Hill Invitational in 1996.

Johnson, 25, won the 2008 Turning Stone Championship in only his second year after turning professional, and is bidding to become the first successful defender at Pebble Beach since Mark O'Meara in 1989-1990.