Phil Mickelson, battling to stay in US Open contention despite an injured wrist, revived briefly before falling victim to toughening conditions at Oakmont in the second round on Friday.
A pair of birdies took three-times major winner Mickelson to two over par for the tournament by the sixth hole, but a double-bogey at seven and bogeys at eight and nine dropped the big left-hander to six over par - eight shots off the pace.
First-round leader Nick Dougherty took best advantage of rain-softened greens on Thursday with a two-under-par 68 that gave him a one-stroke lead over Angel Cabrera of Argentina.
Only two players matched par in the first round - twice Masters champion Jose Maria Olazabal of Spain and American Bubba Watson. Sunshine and lively breezes were combining to firm up the difficult Oakmont layout and low scores could become even scarcer.
Approach shots were bounding through some of Oakmont's fast, undulating greens and putts were speeding by holes and running off the slippery slopes for the early starters. Dougherty, 25, was set to tee off at 1:03 pm local time (1703 GMT), with Cabrera following him off the 10th tee 55 minutes later.
World number one Tiger Woods and defending champion Geoff Ogilvy of Australia, who were among a large group on one-over 71, were teeing off together at 1:36 pm (1736 GMT).
Mickelson, who hurt his left wrist practising out of Oakmont's deep rough in preparation two weeks ago, made a 15-foot downhill putt for birdie at the fourth, and an eight-footer from above the hole for birdie at the sixth. The charge by Mickelson, who squandered the lead in last year's Open at Winged Foot with a double-bogey at the last hole, went in reverse from the seventh hole.
His tee shot landed in an awkward lie in the left rough at the 479-yard par-four. His next shot landed in a ditch and he took a penalty drop on his way to double-bogey. Bogeys followed at eight and nine, and Mickelson was suddenly fighting to stay on the right side of the cut line. The top 60 players and ties, and anyone within 10 shots of the lead qualify for weekend play. Briton Paul Casey was having the best day among early starters at three-under through 11 holes, and four-over for the tournament.