By Mark Lamport-Stokes
OAKMONT, Pennsylvania (Reuters) - PGA Tour rookie Andrew Landry needed just one shot to set the clubhouse lead on Friday as the players returned to a soggy Oakmont Country Club with a marathon day shaping up at the weather-hit U.S. Open.
When play was finally suspended on Thursday after thunderstorms had caused three weather delays in the year's second major championship, Landry was lining up a 10-foot birdie putt on his final hole, the par-four ninth.
After returning to a rain-softened and receptive course on an overcast Friday morning, the 28-year-old American coolly sank the putt to card a four-under 66 for an early one-stroke lead.
England's former world number one Lee Westwood was alone in second place after making birdies on his last two holes for a 67 while Ireland's Shane Lowry carded a 68.
Among the other big names in the field, defending champion Jordan Spieth opened with a 72, 2011 winner Rory McIlroy struggled to a 77 that included eight bogeys and Masters champion Danny Willett returned a 75.
Landry's opening round was the lowest ever in a U.S. Open played at Oakmont, eclipsing the 67s shot by American Ben Hogan in 1953 and South African Gary Player in 1973.
"Just making putts," Landry told reporters when asked what had been the key to his impressive start in his first U.S. Open. "Game all-around was sharp, from tee to green to chipping to everything you do.
"I think the U.S. Open just suits my game so well that I'm just able to manage these things because I'm not a guy that's going to go out and shoot 60 and 61 and 62.
"I'm just a consistent guy that's going to shoot 68 and make a lot of pars."
Landry, who earned his spot at Oakmont via a sectional qualifier in Memphis, said he had spent very little time thinking about his birdie putt overnight.
"I just kind of thought about it this morning a little bit," he smiled. "I read the putt yesterday. I knew what it was doing.
"I knew it was a cup-and-a-half out to the right, so no big break. It was a pretty easy putt to make if you get the speed right."
Twice Masters champion Bubba Watson launched his U.S. Open title bid with a 69, finishing level with fellow Americans Kevin Streelman and amateur Scottie Scheffler, and New Zealand's Danny Lee.
With only nine players having completed the opening round on Thursday, organizers are scrambling to get the tournament back on track and hope to get the second round finished by early afternoon on Saturday.
Weather conditions are expected to improve with mainly sunshine forecast for the weekend.
(Editing by Clare Fallon)