On 17 May 2008, at Buffalo Bill's Star Arena in Primm, Nevada, Gamboa fought Darling Jimenez. Gamboa started off well in the first three rounds of the fight, swarming Jimenez and hitting him with punches over and over but got careless and was knocked down by a right hand behind the ear from Jimenez. Gamboa got up and finished the fight strong, winning by unanimous decision and claiming the vacant WBC International super featherweight title. After the fight, Gamboa's promoter Ahmet Öner fired Gamboa's trainer Osmiri Fernandez, replacing him with Ismeal Salas. On 18 July 2008, stepping down to featherweight, Gamboa scored a first-round technical knockout (TKO) victory over Al Seeger to win the vacant WBO-NABO featherweight title at Buffalo Bill's Star Arena. A left hook to the body set up a right hand that landed across Seeger's face, causing him to collapse backwards flat onto the canvas. The referee stepped over Seeger without bothering to count, officially stopping the bout.