In 1973, Holtzman led the A's with a 2.97 ERA (6th best in the league) as each of their three top starters won 20 or more games. He was again an All-Star, going 21–13 in 40 starts (his 21 wins 4th-best in the AL) with 157 strikeouts. Over the next 33 years only two other left-handers had as many starts in a season. In the 1973 ALCS against the Baltimore Orioles, he won an 11-inning 2–1 duel against Mike Cuellar in Game 3 when Bert Campaneris homered to lead off the last inning. He started three times in the 1973 World Series against the Mets, winning Game 1 2–1. He lasted only ⅓ of an inning in Game 4, departing after a 3-run homer by Rusty Staub, which was followed by two more base runners. He recovered to win Game 7, leaving in the 6th inning with a 5–1 lead as the A's won the game 5–2 and their second straight title. In both his victories, he doubled and also scored the first run for the A's after not having batted all season due to the American League using the designated hitter for the first time in the 1973 season.