A hole-in-one helped Dustin Johnson keep a share of the lead, but only Steve Stricker was home and dry with a 10-under par second-round total on Friday at rainy Riviera Country Club.

First-round leader Johnson had two holes remaining when darkness halted play with 41 players still on the course.

Stricker, the world number three who finished runner-up to Phil Mickelson at the event last year, moved atop the leaderboard with a masterful display in the cold, soggy conditions, posting a six-under 65 for 132.

The rain started just as Stricker was preparing to tee off and didn't stop.

"I'm very happy to be done with the round to tell you the truth. It was pretty miserable out there today," said Stricker, who noted it was unusual on the US tour to play 18 holes in the rain.

"Usually they call it because of lightning or the course gets too wet or something," he said. "This was pretty bad, pretty miserable."

There was nothing miserable about his score, however, an effort that included seven birdies.

He launched his round at the 10th, where he holed a putt from the fringe for a par, and he chipped in for birdie at 18, where his three-wood came up short of the green.

"I think the key for the round was chipping in at 18 for the birdie and making the turn at two-under, then birdieing No.1, that couple-hole stretch there kind of got me going."

At the par-five first, he laid up and chipped to about a foot. Stricker added three more birdies in a round that South African Ernie Els called "unbelievable."

"That's really good golf," Els said. "Breaking par is tough today."

Johnson was impressive as well, keeping pace thanks in part to his ace at the par-three sixth - where his eight-iron from 152 yards landed behind the hole and spun back in.

"That always helps the round a little bit," Johnson said.

Argentina's Andres Romero was lying third at seven-under through 15 holes.

England's Justin Rose, New Zealand's Tim Wilkinson and Kevin Stadler were in the clubhouse on six-under 136.

Rose and Wilkinson both climbed up the leaderboard with four-under 67s, while Stadler shot an even-par 71.

Anthony Kim (66), Ricky Barnes (71) and Steve Marino (67) were on five-under 137, while Japanese teen phenom Ryo Ishikawa was five-under with five to play.

World number two Phil Mickelson, seeking an unprecedented third straight title at Riviera, did himself some good with a five-under 66 for 138.

"I'm in a position where a good round tomorrow and I can get in contention for Sunday, so that's where I wanted to get myself," Mickelson said.

Johnson said the key in the rain, which included some heavy bursts, was patience.

"You're going to hit bad golf shots," he said. "The club is going to slip, foot is going to slip, something is going to happen. You've got to stay patient and try not to get frustrated."

Stricker concurred.

"It's just not as easy swinging on a day like today compared to a 70-degree sunny day," he said. "Your body feels different, the club feels different in your hands, so you're going to miss shots. So a good short game and patience is key."