World Number One Dustin Johnson saw his lead cut to two shots by Justin Rose as the leaders got their rounds under way on day three of the US Open.
The American arrived at Shinnecock Hills Golf Club with a commanding four-shot lead but a double-bogey on the second dropped him to two under after three holes.
Rose - the 2013 champion - made a birdie on the third to sit at level par and be the nearest challenger, one shot ahead of fellow European Tour Members Tommy Fleetwood and Henrik Stenson, and defending champion Brooks Koepka.
England's Ian Poulter, Australian Marc Leishman and American Charley Hoffman were then at two over.
American duo Daniel Berger and Tony Finau both proved there was a low score out there, matching the lowest round of the week with a pair of 66s to set the clubhouse target at three over before the leaders has teed off.
Rose hit an uncharacteristically poor second into the first, leaving himself a 46-yard up-and down for par but he made it to stay at one over.
Hoffman put his second on the first into a bunker and left his ball in there with his third, surrendering a bogey which left Piercy as the only player within four shots of Johnson.
Rose soon changed that, playing a fairway wood from just off the third green for a birdie.
There was then huge drama on the second, with both of the leading group missing the green off the tee. Johnson was on a path to the right and while he played a smart second, three putts led to a double-bogey, with Piercy also three-putting to drop two shots.
Koepka had bogeyed the first but holed a 30-footer with a huge right-to-left break on the second to get back to one over.
Reigning Race to Dubai champion Fleetwood and Swede Stenson both began their rounds with four pars.
Hoffman made another bogey on third, with Poulter bogeying the second and fourth but bouncing back with a birdie on the next.
Leishman sandwiched a bogey on the fourth with birdies on the first and fifth in his first seven holes.
Piercy dropped another shot on the third to drop alongside Berger, Finau and another American in Russell Henley.
