PGA Tour rookie Ricky Barnes posted the target to shoot for at the rain-hit US Open halfway mark as Tiger Woods began his second round hoping to beat approaching storms and the halfway cut.

Barnes, the 2002 US Amateur champion who earned his tour card this year after six years as a professional, shot a five-under-par second-round 65 in the best of the conditions playing back-to-back rounds on Friday and Saturday morning at Bethpage Black.

The American leads at eight under par, one shot ahead of overnight leader Lucas Glover, who posted a six-under-par 64, and another shot in front of first-round leader Mike Weir, the 2003 Masters champion from Canada who added a 70 to his opening 64.

Barnes, 28, began the day in second place at five under and carded birdies at his 11th and 14th and 17th holes as he closed over the front nine.

With the halfway cut determined by the low 60 scorers and ties, defending champion Woods found himself on the projected cut line at four over par, after a birdie at his fourth was followed by a bogey at the sixth as light rain began to fall.

With the skies over Long Island darkening, the leaderboard was dominated by Barnes' initially late-starting side of the draw.

In addition to the top three, Japan's Azuma Yano shot a 65 to get to three under alongside former Open champion David Duval, who added a 70 to his opening 67, and Peter Hanson of Sweden, who finished with a 71.

England's Ross Fisher shot a two-under 68 to take a share of seventh place at two under with American amateur Nick Taylor, following a 65, with former Open champion Todd Hamilton and Sean O'Hair at two under.

World number two Phil Mickelson carded a 70 to get to one under par while fellow American Gary Woodland was also on that mark after carding a 66, with Australia's Michael Sim and Englishman Lee Westwood the only players still out on the course to have crept onto the leaderboard.

Westwood birdied his first three holes to get to one under after five while Sim was two under after 10 holes.