Boston’s Kyle Schwarber, 18, celebrates a grand slam against the Houston Astros in the second inning Monday night in Boston. Robert F. Bukaty/Associated Press

BOSTON — Kyle Schwarber hit a grand slam – Boston’s third in two games —–and the Red Sox routed the Houston Astros for the second straight time, winning 12-3 on Monday night to take a 2-1 lead in the best-of-seven AL Championship Series.

One game after J.D. Martinez and Rafael Devers each cleared the bases, Schwarber hit a second-inning 3-0 pitch 430 feet into the right-field grandstand. Boston is the first team ever with three slams in a postseason series.

Martinez and Devers each homered again, Christian Arroyo also hit one, and Kiké Hernández had two more hits for Boston, which could advance to the World Series with victories at Fenway Park in Games 4 and 5 on Tuesday night and Wednesday. The Astros need to win at least one to send the series back to Houston.

Red Sox starter Eduardo Rodriguez gave up five hits, including Kyle Tucker’s three-run homer, and struck out seven. He retired Carlos Correa to end the sixth and walked off the mound tapping his wrist to clap back at the Astros shortstop, who used the same gesture after a tie-breaking homer in Game 1 to signal that it was Houston’s time.

Things have changed.

The Red Sox had 11 hits in all, becoming the first team in major league history to reach double digits six straight times in a single postseason. Hernandez has 18 hits during the playoffs and is batting .500, both leading the majors.

Capitalizing on two Astros errors and the struggles of Houston starter José Urquidy, the Red Sox opened a 9-0 lead for the second game in a row.

Rodriguez, who missed all of last season with COVID-related heart problems, retired the first six batters before running into the trouble in the third, when Tucker made it 9-3.

Rodriguez’s effort enabled Red Sox Manager Alex Cora – celebrating his 46th birthday – to keep Nick Pivetta fresh for a Game 4 start. Urquidy gave up six runs, five earned, on five hits and two walks, striking out one in 1 2/3 innings.

Right fielder Hunter Renfroe ended the game with a diving catch on Correa’s liner.