Right-hander Clay Buchholz will remain in the Boston Red Sox rotation despite his early innings struggles, manager John Farrell announced Sunday.

Buchholz gave up five runs — Carlos Correa hit a solo homer and George Springer a grand slam for the Houston Astros — in the first two innings of Boston’s 11-inning win on Saturday.

There were boos as Buchholz walked off the mound in the second. He was charged with five runs in six innings, holding Houston scoreless over his final four.

Buchholz (2-3) has surrendered eight home runs after giving up six in 18 starts a season ago and is sporting the worst strikeout-to-walk ratio (1.60) of his 10-year career, all with the Red Sox. His ERA spiked to 6.11 through eight starts.

“It’s not a matter of stuff. I wouldn’t say it’s pitch selection,” Farrell said. “It comes down to location, and that was the case yesterday, whether it’s throwing behind in counts, a walk mixed in or a pitch that leaks back to the middle of the plate and is squared up. And it’s seemingly showing its head in the first couple of innings.”

Buchholz has given up 19 runs in the first two innings of games and just 12 in innings three through seven, according to ESPN.com.

The Red Sox are waiting on the return of left-hander Eduardo Rodriguez, who suffered a knee injury in spring training.

Farrell said Rodriguez will need at least one more rehab start at Triple-A Pawtucket.

In Saturday’s game, David Ortiz launched a game-winning RBI-double to deep center field in the bottom of the 11th inning and the Red Sox walked off with a 6-5 win over the Astros.

Ortiz also hit a solo home run and an RBI — triple his first three-bagger since 2013 and the 19th of his career — while Xander Bogaerts, Travis Shaw and Mookie Betts each drove in a run for the Red Sox.

Houston led 5-4 before Ortiz drove a pitch from Astros closer Luke Gregerson past the grasp of diving center fielder Jake Marisnick for his triple with two out in the ninth to tie the score, but Hanley Ramirez’s botched bunt attempt forced extra innings.

Bogaerts slapped a two-out, opposite-field single in the 11th and advanced to second on a wild pitch to set up Ortiz’s heroics off Houston’s Michael Feliz (1-1).

Boston’s Koji Uehara (2-1) gave up a hit and a walk and struck out two in an inning.

George Springer hit his second career grand slam and Carlos Correa also socked a solo home run for Houston (15-23).