Mickelson Saves Face for Youth : Regular tour: He shoots a 68 and passes senior leader Stockton.

Much of the talk the last two days has been about senior Dave Stockton scoring better than the players on the regular PGA Tour in the first round.

In the second round of the $1.5-million Mercedes Championships, the youngest player on the course put an end to the talk.

Left-hander Phil Mickelson, from San Diego, overcame erratic tendencies to shoot a four-under-par 68 Friday at La Costa Resort and Spa for a 36-hole total of 138.

A birdie at the long, tough par-four 18th put Mickelson, 23, at six under par, one shot ahead of Stockton--who remains the senior leader--and one ahead of three others in the regular tour event.

Fred Couples, regaining control of his game on the back nine; Fiji’s Vijay Singh, among the co-leaders after the first round; and Grant Waite of New Zealand are at 139. Couples birdied Nos. 11, 12 and 17 to post a 70 to go with his 69 in the first round. Singh bogeyed the last hole to wind up with the same figures. Waite shot a 69 after his first-round 70.

Defending champion Davis Love III also shot a second-round 69 and is tied with Billy Mayfair at 140. Ben Crenshaw and Tom Kite are among four players at 141. At the halfway point, there are 16 golfers within five shots of the leader.

“I think it’s neat that the seniors are doing so well,” said Mickelson, who won the Buick of California event at his home course, Torrey Pines, just down the road to get into this tournament.

“I didn’t realize until today that the seniors were playing from the same tee. I had always been curious about how they would stack up with us. I had always heard they played shorter courses. But they are not that far behind us. I think it’s great.”

Until he surprised everyone while still a student at Arizona State and won at Tucson to qualify for the then Tournament of Champions of 1992, Mickelson had played only one round at La Costa.

“It’s not that easy to get on,” Mickelson said. “So, I don’t know why I am doing so well. I really haven’t played since Thanksgiving time, when I was in Japan. I spent last week skiing in Utah.

“Sometimes, taking time off is a blessing. While gliding down the slopes my mind is on golf and the changes I want to make.

“I’m not concerned with winning tournaments as much as I am with improving my game.

“I think the other guys on the regular tour are like me. We’re erratic this early in the year.”

On the first five holes of the second round, Mickelson had two birdies and two bogeys. But on the 398-yard eighth hole, he started to warm to his task. He had three birdies in a row, then had another at No. 13 before the eight-foot putt on the last hole put him in front of everybody.

Couples and Singh figure to pressure Mickelson. Couples, saying he felt better after battling flu, rallied on the back nine. Singh, the long hitter who has moved from Fiji to London, has been playing brilliantly for nearly a year.

Kite, who was one of four players to shoot a 68 Friday, also figures to be in contention.

At one time early in the day it seemed that Greg Norman might be ready to take charge. He surged to five under par going to the 180-yard 11th hole. But he hit his tee shot into the water and started a drop to finish at 143.

36-Hole Leaders at La Costa

PGA TOUR (Player: Score)

Phil Mickelson: 70-68--138 Grant Waite: 70-69--139 Fred Couples: 69-70--139 Vijay Singh: 69-70--139 Billy Mayfair: 72-68--140 Davis Love III: 71-69--140 Tom Kite: 73-68--141 Ben Crenshaw: 71-70--141 John Inman: 71-70--141 Brett Ogle: 69-72--141 Jim Gallagher: 73-69--142 Jay Haas: 71-71--142 Scott Simpson: 70-72--142

Four tied at 143

SENIORS (Player: Score)

Dave Stockton: 67-72--139 Dale Douglass: 71-69--140 Bob Murphy: 71-70--141 Jack Nicklaus: 73-69--142 Lee Trevino: 71-71--142 Bob Charles: 70-72--142 George Archer: 71-73--144

Three tied at 145