Thornton's production declined to 73 points in 77 games in the 2003–04 campaign. He suffered a fractured right cheekbone in a fight with New York Rangers centre Eric Lindros during a game on January 19, 2004. The two power forwards fought after Lindros cross-checked Thornton in the head. The injury required surgery, keeping him out of the line-up for three games. The 2003–04 campaign also saw a drop in Thornton's goal-scoring production that has never since rebounded; his last 30-goal season came during the 2002–03 season.