Ranked at a career-best 46th for the 1990/1991 season, Marshall defeated Tony Wilson of the Isle of Man, fellow Englishman Mark Johnston-Allen and South African Peter Francisco - all 10–9 - to qualify for the main stages of the 1991 World Championship, his first appearance at the Crucible Theatre. In his last-32 match against Reynolds, he led 4–2 but went on to lose 8–10.