John started his professional career at Dutch first division side FC Twente as a 17-year-old, going on to score 11 league goals during one-and-a-half seasons combined. He was signed by Fulham on 31 January 2004, cited by manager Chris Coleman as a way to expand attacking options in the future. He signed for a fee thought to be in the region of £600,000 where he was introduced at Loftus Road by John Collins, his reverse namesake. His debut for the club came as a substitute for Mark Pembridge against Chelsea in a 2–1 defeat at Stamford Bridge on 20 March.