Complex sentence: On 25 June 2005, he entered the popular consciousness of boxing fans with a controversial upset KO against WBA Light Welterweight titlist, Vivian Harris, making Maussa a new champion in boxing's most competitive division.
Split into simpler sentences: On 25 June 2005, he entered the popular consciousness of boxing fans with a controversial upset KO against WBA Light Welterweight titlist, Vivian Harris. This exciting victory made Maussa a new champion in boxing's most competitive division.