Phil Mickelson surged into early contention at the Saudi International, recovering from an unsteady start in Thursday's opening round.
Reported to be pocketing a huge appearance fee at the European Tour event this week, Mickelson could boost his earnings with a first professional win in close to a year.
The 49-year-old five-time major winner began slowly and reached the turn with a two-over 37 after a double bogey at the second was followed by a pair of birdies and two more dropped shots.
However, he then made six birdies in seven holes from the 10th to 16th, adding another at the 18th, and with only one blemish on the back nine, he carded a four-under 66 to sit two off the lead.
At the short 11th, Mickelson's tee shot struck the flag and almost dropped in for a hole-in-one. He made the two-foot putt for birdie.
Tiger Woods and Rory McIlroy are among the players who turned down big money to play this week, and Mickelson's appearance - reportedly worth $3million - means he is absent from the Phoenix Open for the first time since 1990.
He last won a tournament in February 2019 at Pebble Beach.
Political considerations may have been a factor in some players missing the Saudi event, with McIlroy saying in December that "one hundred per cent, there's a morality to it". Saudi Arabia's human rights record has been heavily criticised by Amnesty International.
A strong field has nevertheless assembled, with Malaysian Gavin Green and Northern Ireland's Graeme McDowell setting the early pace.
Six-under rounds of 64 nudged them one clear of Frenchman Victor Perez, Venezuelan Jhonattan Vegas, Sweden's Henrik Stenson and Sebastian Soderberg, and Spain's Adri Arnaus.
Mickelson sat tied for eighth in a group of six that also contained England's Andy Sullivan and Ross Fisher.
The Open champion Shane Lowry and former Masters winner Sergio Garcia were both one under, with world number one Brooks Koepka on even par, the same mark as Lee Westwood.