Eagles made his first-team debut for Manchester United on 28 October 2003 as a second-half substitute for Kieran Richardson in an extra-time win away to Leeds United in the League Cup. He played once more that season, this time as a substitute for Cristiano Ronaldo as United lost 2–0 away to West Bromwich Albion in the Fourth Round of the League Cup. His performances saw him nominated for the new League Cup talent award, awarded to the young player judged to have made the best first-team breakthrough in the competition. He played in the 2004 FA Community Shield, coming on as a 74th minute substitute in a 3–1 defeat by Arsenal at the Millennium Stadium.