Chad Campbell kept his head to maintain his place at the top of the leaderboard midway through the second round of the Masters on Friday.
The American, who led by one shot after the first round on 7- under-par, moved to 9-under after a 70, thanks in no small part to a birdie at the last hole.
His lead could and should have been more after four birdies in the first 10 holes took him to 11-under. But bogeys at 11, 12 and 17 dropped him back before his final-hole birdie took him back to 9- under.
The birdie could yet prove crucial for many of the field because the halfway cut line will be drawn to include the top 44, plus ties and anyone within 10 shots of the lead.
Former Open champion Todd Hamilton was his closest challenger in the clubhouse after a 70 left him 6-under-par.
On the course, another American, Kenny Perry, was 7-under-par through 13 holes, while tournament favourite Tiger Woods was 2-under- par after 12 holes of his second round.
Open champion Padraig Harrington was level for his round, 3-under- par for the tournament, one ahead of Irish teenager Rory McIloy, who picked up two early shots in his first 12 holes.
Two-time champion Phil Mickelson was just beginning his second round, with work to do to get back into contention after his opening- round 73, reported dpa.