A two-under-par round of 70 was good enough to see Canada's Stephen Ames tied at sixth, just two shots off the lead after the first round of the US Masters.

The first year's golf major saw beautiful springlike conditions at Augusta, Georgia, but no player broke from the pack to tame the course. Even Tiger Woods, winner of seven out of his past eight tournaments, found the going tricky, carding a level-par round of 72.

Calgary's Ames had a great start to the 2008 season, finishing third at the Mercedes-Benz championship in Hawaii in January, but has not hit those heights since then.

Englishman Justin Rose and South Africa's Trevor Immelman were Thursday night's clubhouse leaders.