With the 1990 FIFA World Cup being held on home soil, Vialli named part of the squad and he was expected to make a huge impact for the hosts. However, after failing to score in the first match against Austria, despite setting up the winning goal via a cross, Vialli missed a penalty against the United States in the next match, hitting the lower near post with keeper Tony Meola diving the other way. He was subsequently dropped from the team in favour of Roberto Baggio and Salvatore Schillaci, who had scored the winning goal against Austria after appearing as a substitute. Vialli returned to the team for the semi-final against Argentina and played a role in Italy's opening goal after his shot on goal was blocked by Argentina keeper Goycochea and the rebound fell to Schillaci. He was substituted in the second half as Italy were eliminated on penalties, eventually finishing the tournament in third place. Because Italy assigned jersey numbers alphabetically to players for the World Cup (beginning with defenders, then midfielders, and finally attackers) Vialli wore the number 21 during the World Cup. Overall, he finished the tournament with 2 assists, which were both provided for the golden boot winner Schilacci.