Phil Mickelson doggedly held on to the lead for a third day in California, going round the PGA West Stadium Course in 66.
Having carded a level career-best 60 on day one, the American shaved two shots off his day two total to sit two ahead at the top of the pack.
With the cut at -9, Seamus Power was well off the pace. A round of 71 was his best of the three rounds, with four birdies, a bogey and a double bogey at the ninth as he finished on 11-over par.
Mickelson managed the first of two rounds of the Stadium Course without blotting his copybook, carding three birdies on the opening nine and another trio on the way back.
Canada's Adam Hadwin carded a 65 to climb into second, while Adam Long of the US is just behind after completing La Quinta Country Club in 63.
Scotsman Russell Knox surged up the leaderboard to tie for 19th after going round the Nicklaus Tournament Course in 64.
Meanwhile England's Justin Rose dropped down one place after carding a 68 at the Stadium Course.
The Desert Classic is a pro-am tournament with 72 holes played over three courses; the Nicklaus, La Quinta and the Stadium Course at PGA West.
