By February 1985, he had started just eight games in the 1984–85 season, having fallen behind in the pecking order to Stapleton, Hughes, and new signing Alan Brazil. However, injury to midfielder Remi Moses left an opening at the centre of the field, and Whiteside proved to be a revelation in the role with his intelligent play and positioning skills, and stayed in midfield for the rest of manager Ron Atkinson's time at the club. He formed a solid partnership with Bryan Robson, despite the two being similarly attacking players, and United lost just one of their first 15 games with this new midfield partnership in operation. Whiteside scored the only hat-trick of his professional career in a 4–2 home win over West Ham United on 9 March 1985, in the FA Cup quarter-finals; it was a 'perfect hat-trick' in that he scored once with each foot and once with his head. He went on to score the winning goal in the 1985 FA Cup Final, curling a shot in from the right hand side in the 20th minute of extra time, to give ten-man United victory over Everton, and Whiteside his second FA Cup winner's medal. The goal required vision, timing, and precise shooting; and "The Guardian" praised his "cool footballing brain" and "clever concealment of the shot". After this success he negotiated a new contract of £60,000 a year.