Lupoli's debut in the Arsenal first-team was in a match against Manchester City in the League Cup on 27 October 2004. His next match, against Everton in the same competition, brought him his first goals for the club, two of Arsenal's three goals in the 3–1 victory on 9 November. He also played in the match against Manchester United which saw Arsenal's exit from the competition. He was Arsenal's top scorer at youth/reserve level in 2004–05, with 27 goals in 32 appearances. That season he started Arsenal's FA Cup fifth round replay against Sheffield United due to Robin van Persie, Dennis Bergkamp and Jose Antonio Reyes all being suspended, and Thierry Henry being injured. Arsenal went on to win the cup that year but Lupoli was left out of their final squad.