Farmingdale, New York - American Ricky Barnes found himself in an unlikely position at the top of the leaderboard midway through the second round of the US Open at Bethpage on Saturday.

Barnes picked up where he left off the previous night, adding three more birdies in his closing 10 holes to set the target on 8-under-par after a brilliant 65.

The American was one shot clear of overnight leader Lucas Glover, who completed a flawless round of 64. Former Masters champion Mike Weir was a shot further back after a 70 and the former Open champion David Duval is right there on 3-under-par after a 70.

With the 10-shot rule in operation - all players within 10 shots of the leader make the final two rounds - several big names have a lot of work to do if they are to qualify.

The biggest of these is the defending champion, Tiger Woods, who was due to begin his second round on Saturday on 4-over-par.

Phil Mickelson is in a much stronger position on 1-under-par after a 70 to follow his opening-round 69.

Sergio Garcia was on level par after a second successive 70, while Australian Adam Scott finished on the same score. (dpa)