During the regular season, Devers appeared in 121 games, batting .240 with 21 home runs and 66 RBIs. On defense, he led the major leagues in errors, with 24. He also had the lowest fielding percentage among major league third basemen, at .926. He performed much better in the postseason, becoming the fifth player to hit at least three home runs before his 22nd birthday. In Game 5 of the 2018 ALCS, Devers hit a go-ahead three-run home run in the sixth inning, helping to send the Red Sox to the World Series. In Game 4 of the World Series, Devers became the youngest player with a go-ahead RBI in the 9th inning or later of a World Series game since Édgar Rentería's walk-off single in Game 7 of the 1997 World Series. The Red Sox won the series in five games over the Los Angeles Dodgers, giving Devers his first championship title.