Martinez turned professional in December 1997 in Ituzaingo, Buenos Aires, Argentina. In his debut Martinez defeated Cristian Marcelo Vivas with a second round stoppage.[2]
Following 17 straight victories against relatively low level opposition in Buenos Aires within a two year period, MartÃnez then fought his first fight outside of Argentina against upcoming boxer Antonio Margarito at the Mandalay Bay Resort & Casino in Las Vegas, Nevada, United States in February 2000. MartÃnez slumped to his first defeat when he suffered a 7th round knockout to the Mexican.[2]
On May 21, 2009, WBC Super Welterweight Champion Vernon Forrest was stripped of his title due to a rib injury that would leave him out of action indefinitely. Because of the injury and his inability to fight Sergio Martinez, Martinez’s interim title was upgraded to full WBC Title status.
He received a controversial Majority Draw against Kermit Cintron of Puerto Rico on February 14, 2009.
On December 5th Martinez fought Paul Williams in a war of a twelve round main event. In the first round Martinez was knocked down due to bad balance and a grazing left hand. In the final seconds of the 1st round though Martinez scored a knockdown of his own over Williams. The next two rounds were heavily in Martinez’s favor as he hit Williams with barrages of counter punches. Rounds 4-7 showed Williams coming back effectively landing hard lefts to the head of Martinez. In rounds 8-11 Martinez again confused Williams with using different varieties of punches including; straight lead lefts to the body followed by right hooks to the head and straight lefts to the face. The 12th and final round showed much fatigue in Martinez and Williams but the warriors fought through to the end. Williams won a close majority decision over Martinez with the judges scoring; Pierre Benoist 119-110 for Williams, Lynn Carter 115-113 for Williams and Julie Lederman 114-114. Afterward both fighters expressed interest in a possible rematch.
