American golfer Bo van Pelt faces a stern challenge on several fronts as he attempts to defend his Perth International title.

Van Pelt teed off at the $2 million tournament at Lake Karrinyup CC on Thursday morning, with his three-man group containing fellow pre-tournament favourites in American Dustin Johnson and Australian Brett Rumford.

Johnson is ranked 21st in the world and has seven US PGA Tour wins under his belt, while Rumford is enjoying a career-best year that’s included two wins on the European Tour.

Others major threats to van Pelt’s title defence include rising South African star Branden Grace, 12-time European Tour winner Paul Casey, and England’s Ross Fisher.

Johnson shares the early lead at one-under after two holes, while van Pelt and Rumford are even with the card.