Lee left Manchester City in 1974, joining Derby County. For the second time in his career, Lee joined a team viewed as contenders for that season's league title. He was upset at Manchester City's decision to sell him and marked his first match against his former club by scoring the winning goal for Derby. Lee scored twelve league goals that season, Derby winning their second League title and Lee the second championship medal of his career. On 1 November 1975, Lee had a confrontation with Leeds United defender Norman Hunter, which gained a level of infamy after it was screened on Match of the Day. In the first half of the game, the referee adjudged that Hunter had fouled Lee in the Leeds penalty area, and awarded Derby a penalty. Charlie George, and not Lee, took the penalty kick, and scored. In the second half, Lee and Hunter were seen to be exchanging punches in an off-the-ball incident. The referee stopped the game and took both players' names, but it was not immediately clear if he had sent off either or both of them. However, as the two men walked away they began fighting again. After intervention by both sets of players, Hunter left the pitch and Lee was restrained and ushered off the field by a club official. In 2003, the incident was named by The Observer as sport's most spectacular dismissal.
