Complex sentence: The 2003 Open Championship was Curtis' first appearance in a major; he became the first golfer since Francis Ouimet in the 1913 U.S. Open to win his major championship debut, later accomplished by Keegan Bradley in the 2011 PGA Championship.
Split into simpler sentences: The 2003 Open Championship was Curtis' first appearance in a major. He became the first golfer since Francis Ouimet in the 1913 U.S. Open to win his major championship debut, later accomplished by Keegan Bradley in the 2011 PGA Championship.