Luke Donald dropped two shots on Friday morning to fall one behind Phil Mickelson after the completion of his first round.
The former world number one ended the opening day on three-under-par, but was left with five holes to play after thunder storms forced two delays.
Donald returned to par the 14th and 15th hole as he attempted to stay ahead of the American, who held the clubhouse lead after Thursday's play.
However, a five on the par-four 16th brought him back level with the left-hander, but he replied with a par on the penultimate hole.
He found the green in two on the final hole, but a disappointing three-putt saw him lose the tournament lead.
