Phil Mickelson is focused on performing well at the WGC-Bridgestone Invitational this weekend, rather than usurping Tiger Woods at the top of the world rankings.
The 40-year-old left-hander was on course to wrest the world No1 ranking from Woods after moving one shot behind halfway leader Retief Goosen at Firestone Country Club in Akron, Ohio.
A top-four finish, coupled with Woods finishing outside the top 44, would see Mickelson climb from second in the world to top spot. Mickelson was on six under with 36 holes to play after a second round 68 saw him sit joint second alongside Justin Leonard (66) and one behind South African Goosen, who was on seven under after rounds of 67 and 66.
Woods, meanwhile, signed for a two over par 72 and was 13 strokes off the lead on six over and in a tie for 72nd.
Although Mickelson is poised to end Woods' 270-week reign at the top of the rankings, he is first concentrating on finding form for next week's USPGA Championship at Whistling Straits, Wisconsin.
Mickelson said: "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) I try not to think about it.
"I want to come out and play well here, get in contention, get sharp, get focused, especially for next week, too.
"But also, this is a World Golf Championship event that means a lot, and I'd like to make a move this weekend."
Goosen, who has seven PGA Tour career wins and has finished in the top 10 on seven occasions this year, was in pole position for victory at the halfway stage. "This would be a great event to get my first win for the year," he said.
Lee Westwood, who, like Mickelson, had an opportunity to seize the world No1 ranking, withdrew with a ruptured plantaris muscle in his right calf. The 37-year-old Englishman even hinted his participation in the Ryder Cup in October could be in doubt due to the injury, which he suffered at the end of June.
Rory McIlroy enjoyed a roller-coaster ride, while Graeme McDowell nosedived out of contention with an erratic driving display on day two.
Mcllroy signed for a card showing four birdies and three bogeys in a one-under-par 69 for a three-under-par tally around the Firestone course. It left the present world No8 lying just four strokes behind Goosen.
McDowell let slip his share of second place with five bogeys and just two birdies in his 73. A day earlier, the current US Open champion had finished with four straight birdies, but McDowell ended day two with a pair of bogeys. "I was sloppy and just missed too many fairways," he said.