After not defending his title for a year and a half, he was forced by the WBA to defend his title or be stripped of it. He chose to defend it, despite his problems making the weight. On 3 March 1986, Sandoval defended his title against Gaby Canizales, as part of a super-undercard organized by promoter Bob Arum, which included the Hearns versus Shuler and Hagler versus Mugabi encounters. Sandoval reportedly had to lose around twelve pounds in three days in order to be able to fight that night, staying off any solid foods and surviving only on water. Weakened and feeling the side-effects of such a sudden drop-off in weight, Sandoval suffered four knockdowns, but he fought on until the fifth knockdown, which happened in round seven, after which the referee stopped the fight. He fell unconscious a few minutes after the fight, stopping breathing for an estimated three minutes. He was rushed to hospital by local on-site paramedics, but he remained in critical condition for the next few nights. He had life-saving brain surgery, but the inevitable consequence was that Sandoval was obliged to retire. His final record was 29 wins and one loss, 17 wins by knockout.