With his unique double-handed playing style, Marshall finished runner-up to the great Pakistani player Jansher Khan at the World Open in 1994 and the British Open in 1995. When he reached the World No. 2 ranking behind Jansher in November 1994, many observers felt he seemed a strong candidate to displace the aging Pakistani champion as World No. 1. However, in 1995, Marshall was afflicted with glandular fever, the effects of which meant he was unable to play top-level squash for two years.