The 24-year-old Harvey, 7-2 with a 2.35 ERA and an NL-high 147 strikeouts, will become the youngest All-Star starting pitcher since the Mets' Dwight Gooden in 1988, when he was 23.
Justin Verlander was the AL starter and loser last year. Scherzer (13-1, 3.10 ERA) joins him to become the first pitchers from the same club to start consecutive All-Star games since Arizona's Randy Johnson (2000-01) and Curt Schilling (2002).
Scherzer was 13-0 before losing Saturday to Texas. He had most wins in a perfect start since Clemens won his first 14 decisions in 1986.