Stacey made his Manchester United debut on 12 October 1907, playing at left back in a 6–1 away win over Newcastle United. That season, he made 18 league appearances and scored one goal as United won the First Division title by nine points over Aston Villa - the first major trophy in Manchester United's history. The following year, Stacey played more regularly at right back, playing in 38 matches on the way to the 1909 FA Cup title. In 1910–11, United won the First Division again, albeit only by one point, with Stacey missing only two matches.