 After three successful defenses, including a decision over the undefeated Lamar Parks, Johnson lost the belt to fellow southpaw John David Jackson.He twice failed in attempts to regain the WBA title, both by hotly disputed decisions to Jorge Castro in Argentina.He later moved up to light heavyweight, winning the IBF title in 1998 against the undefeated William Guthrie with a rare one-punch knockout in the fifth round, a fight in which Guthrie left the ring on a stretcher.