Lee Westwood moved to the top of the leaderboard as he made a bright start to his second round at the US Open at Oakmont Country Club.
The Englishman started the day at three under, a shot behind big-hitting American Dustin Johnson - who completed his second round on Friday - and first-round leader Andrew Landry.
But while Landry turned in 39 to drop to level par, Westwood birdied the first and fourth to hit the summit with four holes of his second round completed.
The 43 year old has two top threes in this event and, like Johnson, is going in hunt of his first Major Championship in Pennsylvania.
It was a second consecutive glorious day on the outskirts of Pittsburgh after the weather delays on Thursday and the drying, firm layout is expected to fully bare its notorious teeth over the weekend.
Westwood made the perfect start as he put a brilliant approach to three feet on the first and then did very well to get up and down and save par on the second.
That opening birdie moved him into a three-way tie for the lead but it was soon a two-way share as Landry found a greenside bunker on the par three sixth and then more trouble off the tee led to another dropped shot on the next.
A double-bogey followed on the eighth as the World Number 624 endured a torrid morning.
Westwood was flying, though, and when he found the green on the par five fourth in two, he made a birdie to move to five under.
Sergio Garcia and Scott Piercy were at two under having completed two rounds, a shot clear of Andy Sullivan, Jim Furyk and Daniel Summerhays.
Shane Lowry, Russell Knox and Bubba Watson were also one under on their front nines.
Louis Oosthuizen had looked in danger of missing the cut early on Friday evening but he went on a run of four birdies from the third and made another gain on the ninth as he finished his second round on Saturday morning.
That handed him a brilliant 65, ten shots better than his opening effort, and flew him up the leaderboard.
It's a good position. Four behind going into any US Open third round is a good place - Louis Oosthuizen
"I didn't have a great first round. I felt as uncomfortable over the golf ball as I have in a while. I couldn't really find anything on the range, as well, before the second round.
"But out on the golf course, I found something in my set-up that felt comfortable, started swinging a bit. I started getting my little cut back on my driver and went from there."
Masters Tournament winner Danny Willett and 2011 champion Rory McIlroy had two birdies in their first three holes to get to three and five over respectively.
World Number Seven Henrik Stenson had to withdraw from the tournament through injury and Tweeted: "Minor neck and knee issues, nothing Major! Hope to be back in action next week!"
