Gamboa managed to connect more punches in every round to keep the scorecards in his favor. Although there were not many exchanges, Gamboa's hand speed and reflexes were on display as he connected with quick and short combinations and managed to avoid some of de León's left swings with his characteristic upper body movement. In the eighth round, during a short exchange, Gamboa and de León accidentally clashed heads, resulting in de León suffering a cut to his forehead, consequently the referee stopped the fight and asked de León's corner to check the boxer's wound. After having tried and failed to stop the bleeding it was determined by de León's team that their fighter was unable to continue in the fight. On 26 October 2011, Gamboa hired world-famous Emanuel Steward as his head trainer. Gamboa was initially set to return in April 2012 against lightweight champion Brandon Rios, but he pulled out of the bout citing problems with his contract with Top Rank. After a long dispute between Gamboa and Top Rank, the two sides agreed to part ways, with Gamboa's contract being bought out for a flat fee. In July 2012, Gamboa signed a promotional contract with 50 Cent and Floyd Mayweather Jr.'s promotional company, "The Money Team Promotions". After the 50 Cent-Mayweather TMT Promotions never came to fruition, 50 Cent decided to make his own promotional company SMS Promotions and officially signed Gamboa. 50 Cent worked with Top Rank's Bob Arum and Mayweather's rival Manny Pacquiao. Gamboa then landed a fight undercard of Pacquiao vs. Marquez 4 on 8 December 2012. He fought Michael Farenas, who fought to a draw in his previous fight with WBA title holder Takashi Uchiyama. Gamboa was show boating throughout the fight while Farenas maintained his focus. Farenas was dropped twice which gave Gamboa more confidence, dropping his hands occasionally. In the ninth round Gamboa tried to finish Farenas off with a barrage of punches but Farenas countered him with a left hook that dropped Gamboa. Gamboa stopped show boating after the ninth round, winning the fight by unanimous decision. As he was moving up to lightweight, Gamboa was linked to performance-enhancing drugs through the Biogenesis scandal, which included Alex Rodriguez. Gamboa eventually moved up in weight to take on undefeated Darleys Pérez (28-0) for the vacant WBA interim lightweight title.