On February 5, 2005, Alexander defeated Donovan Castaneda by unanimous decision in front of 22,370 spectators. He won his next five fights before on July, 2006, at the Savvis Center in St. Louis, Missouri. On January 6, 2007, Alexander defeated Maximinio Cuevas by fourth round technical knockout at the Seminole Hard Rock Hotel and Casino in Hollywood, Florida. He won his next two fights against Marcus Luck and Cory Peterson before he went up against former WBO junior welterweight champion DeMarcus Corley on January 19, 2008, at Madison Square Garden in New York City. In 2009, he defeated Junior Witter by eighth round due to RTD 8 to claim the vacant WBC light welterweight championship. On October 22, 2010, he was stripped of the IBF Junior Welterweight title for not fighting the no. 1 contender, Kaizer Mabuza. On January 29, 2011, his next fight took place against Timothy Bradley, which he lost.
