Amoah was top scorer in the 1999–2000 Nationalliga A, contributing 25 goals to St. Gallen's title-winning season.[2] At St. Gallen he also memorably scored one of the goals and provided an assist as they overturned a 1–0 first-leg deficit to win 2–0 in the second leg and eliminate Premier League side Chelsea from the 2000–01 UEFA Cup.[2][3]