Doug Fister, who spent last season with the Astros, will start Game 3 for Boston, which lost Games 1 and 2 in Houston by identical 8-2 scores.
• Gear up for Astros' postseason
Peacock (13-2, 3.00 ERA) had a breakout season and became one of the Astros' most reliable starters after beginning the season in the bullpen. As a starter, Peacock went 10-2 with a 3.22 ERA in 21 starts, striking out 135 batters in 111 2/3 innings.
"Peacock's really good," Hinch said. "He's had an exceptional season as a starter. He's filled a couple of different roles, and he's earned this start. I think his effectiveness, his calmness, his ability to throw strikes, he's got real weapons, he gets a ton of swing and miss. His is season speaks for itself, which is why we would turn to him in Game 3."
Peacock, who was out of options this spring and narrowly made the Opening Day roster, set career highs for wins, innings (132), strikeouts (161) and appearances (34). He held opposing hitters to a .206 batting average this year, giving up just 10 home runs.
Morton (14-7, 3.62 ERA) set career bests in strikeouts (163), WHIP (1.19), opponents' batting average (.228), strikeouts per nine innings (10) and strikeout-to-walk ratio (3.26).
Brian McTaggart has covered the Astros since 2004, and for MLB.com since 2009. Follow @brianmctaggart on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.