Phil Mickelson recaptured top spot at The Open after nine holes of the third round, having briefly fallen behind playing partner Henrik Stenson.
The overnight leader saw his one-shot advantage wiped out on the first as Stenson birdied to signal his intent at Royal Troon.
And the Swede, who shot Friday's lowest score of 65, moved into sole possession of the lead for the first time at the fourth despite missing an eagle putt, with a birdie enough in light of Mickelson's par.
But dropped shots at the sixth and Postage Stamp eighth, combined with Mickelson staying bogey-free across the front nine, saw the American regain the upper hand.
Mickelson sat 11 under at the turn, with Stenson a stroke back, while reigning champion Zach Johnson's double-bogey six at the Railway Hole all but ended his challenge.
How Phil Mickelson has played the front 9 this week ...-- PGA TOUR (@PGATOUR) July 16, 2016
Bogeys: 0 pic.twitter.com/3E7mvsDb0n
Soren Kjeldsen was initially the nearest challenger to the final duo as he went out in 36, but the Dane then double bogeyed the 10th and slipped back to five under.
That left Bill Haas and Andrew Johnston tied for third, five off the pace, both men having holed out from off the green at the eighth and 13th respectively.
With winds gusting up to 30 miles per hour, the decision was taken not to cut or roll the greens and certain pins and tees were adjusted.
But the field again struggled on the back nine, as the conditions played havoc around the turn with bogeys particularly prominent at 10 and 11.
Rory McIlroy, Open champion in 2014, signed for a 73 to be level par for the tournament. Of the others safely back in the clubhouse, the 68s recorded by Steve Stricker, Brandt Snedeker and Haydn Porteous were the best scores.