 He started his amateur career as early as 1904, and in February 1905 had three round wins on points in Pittsburgh against Frank Walton, and James Harris.On October 18, 1911, Klaus defeated the great contender Leo Houck in a newspaper win by both the "Philadelphia Item" and the "Philadelphia Record".In his career, the Pennsylvania born middleweight fought some of the greatest welter, middle, and light heavyweights of his era, including Jack Dillon, Battling Levinsky, Mike Gibbons, Harry Greb, and Al McCoy.