Charl Schwartzel was the best-placed European Tour Member as Bill Haas compiled a three shot lead at the Northern Trust Open.
Defending champion Haas stormed to the head of the leaderboard with a seven under par 64 in California.
Haas has been steadily improving all week and followed rounds of one under and four under with a blemish-free circuit which was highlighted by an eagle at the par four tenth and gave him a commanding three shot lead on 12 under.
Heading the chase were Webb Simpson, Schwartzel and John Merrick on nine under, with World Number Three Luke Donald and overnight joint leader Fredrik Jacobson a shot behind.
It will be a very different day four from last year for Haas, who 12 months ago faced a two shot deficit and this time has a substantial cushion.
"(It's) very difficult in this game to just pull away from the rest of the field," Haas told www.pgatour.com. "You've only seen a few guys ever really do that. And those are guys like Jack Nicklaus, Tiger Woods, Phil Mickelson.
"So I think I've just got to try to stay in the moment, don't let my emotions get the best of me.
"The guys behind me are going to make birdies and it will certainly get closer at the top. So I've just got to try to hang in there and give myself a chance on the back nine."
The moment of Haas' round, which equalled the lowest of the week, came at the tenth where he chipped in from 57 feet for eagle.
But he is far from comfortable in his number-one status with some illustrious figures in his rear-view mirror.
Leading those are a pair of Major winners in Simpson and Schwartzel, both three under for their third rounds, and Merrick.
Simpson said: "Bill shooting seven under is incredible out there. I mean, it was very tough. I felt like my three under was pretty good."
Donald was fifth overnight and stayed exactly where he was with a one under 70, which put him alongside Jacobson, who carded a 71.
South Korean Bae Sang-moon, who headed the leaderboard alongside Jacobson overnight, had a day to forget as a five over 76, which included a double bogey at the par five 17th, saw him slip to a share of 13th on four under.
World Number Eight Lee Westwood also struggled as his 74 saw him drop to joint 17th on three under, where he sat alongside fellow Englishman Greg Owen.
