He only got one chance in the postseason, and he certainly made the most of it when his Twins faced the St. Louis Cardinals in the World Series. After getting past the Detroit Tigers in the 1987 American League Championship Series, Viola and the Twins had to face the favored Cardinals. Viola pitched Game 1 and led the Twins to a 10–1 rout of the Cards. Viola's second start came in Game 4, and the Twins went on to lose 7–2. After the Twins tied the series in Game 6 with an 11–5 win thanks to a Kent Hrbek grand slam, it was up to Viola in Game 7. He pitched a gem, shutting the Cardinals out after giving up two runs in the second inning. Jeff Reardon pitched the ninth inning, and the Twins won 4–2 on the way to a 4–3 series win. Viola was named World Series MVP.