In search of his first major title, Lee Westwood made seven birdies and finished at 5-under par 67 to grab the first-round lead at the Masters.
Westwood had a one-shot lead over Louis Oosthuizen, who finished birdie-birdie to shoot 68 on Monday.
Paul Lawrie, Miguel Angel Jimenez, Francesco Molinari, Ben Crane and Jason Dufner were in a five-way tie for third on the crowded leaderboard.
The day started calm but damp at Augusta National — normally good scoring conditions that were offset somewhat by mud sticking to the balls in the fairway.
Tiger Woods finished with a pair of bogeys and shot even-par.