The first step is to make up a one-shot deficit against Retief Goosen, the 36-hole leader Friday at the Bridgestone Invitational. Looking more inevitable is Mickelson finally supplanting Tiger Woods atop the world ranking.
Goosen turned bogey into birdie by chipping in from 25 yards off the green at No. 4, sending him on his way to 4-under-par 66 that gave him a one-shot lead over Mickelson (68) and Justin Leonard (66) going into the weekend at Firestone Country Club.
Even as Goosen led another assault on par in soft conditions, Woods continued to look as ordinary as ever. The seven-time champion at Firestone hit only three fairways and stumbled to 72 -- the first time he has ever had consecutive rounds over par at this tournament -- that put him 13 shots out of the lead, and five players removed from last place. There is no cut in this tournament, a World Golf Championship event.
Woods had no intention of speaking to reporters, instead walking to his car and driving away.
He has been No. 1 in the world since the week before the 2005 U.S. Open, but would lose his top ranking if Mickelson were to finish in fourth place alone and Woods --who is tied for 72nd -- finishes out of the top 44.
"Obviously, it would be cool," Mickelson said. "It would be something I would love to do, being regarded as No. 1 according to the ranking. And I know that I've got a great opportunity this week. I know that I'm playing well, and this is my best opportunity."
But he still has 36 holes in front of him on a course that has rewarded good shots with low scores.
Despite a bogey on the final hole, Goosen was at 7-under 133 as he tries to win his first World Golf Championship. It doesn't figure to be easy, not so much because of Firestone, rather the number of players chasing him.
Sixteen players were separated by four shots going into the weekend.
That includes Bubba Watson (71) in the group at 5-under 135, Adam Scott (70), former Clemson golfer Lucas Glover (66) and Paul Casey (68) at 136, and Rory McIlroy (69) and Dustin Johnson (65) in the group at 137.
"Every part of your game needs to be good here, driving especially," Goosen said.
"You need to hit it on the fairway, otherwise you're struggling."