LaRoche contributed an RBI double in the fourth inning that gave the Red Sox a three-run lead over the A's.
On the heels of the trade last week that brought LaRoche to the Red Sox, manager Terry Francona has two lineup spots for three starting-caliber players.
On Friday night, LaRoche was the one on the bench. Youkilis got a rest on Saturday, followed by Lowell the next two days.
Lowell wasn't surprised to be on the bench on Monday, as Francona had given him a heads-up.
"I got a text message yesterday," said Lowell. "I think we're trying to find the best combination for us to win ballgames."
The Red Sox have struggled mightily to score runs of late. Though Lowell has hit .381 since returning from the disabled list on July 17, Francona felt it was best to have LaRoche's left-handed bat in the lineup against A's right-hander Trevor Cahill.
"He's actually doing pretty well," Francona said of Lowell. "He'll be back in there. We're just trying to find ways to score runs. That's not his fault. He's actually swinging the bat pretty good. ... [Cahill] is a lot tougher on righties."
Francona is trying to maximize both wins and the production of his three corner men.
"Rather than just try to make a lineup out to appease personalities, I'd rather just play who I think can help us win tonight," Francona said. "Also, being aware that I don't want to go back and forth [every game] -- because I don't know that's real helpful -- I'd like to try to string some games together. I'm not saying Mikey is going to play tomorrow, [but] I bet you he will. And then have the two lefties in a row. I'm trying to let these guys string together as many at-bats as they can. Sometimes that means sitting more than one night also."
Though Lowell is accustomed to being an everyday player, he understands the current situation and the fact that the Red Sox aren't hitting as a team.
"We're going to see how it goes," Lowell said. "If we keep playing like this, there's going to be major changes in the lineup. We have to start swinging the bats and start scoring runs. I don't think anything is ever etched in stone. I was told I was going to get more days off.
"Like I've said in the past, winning determines who plays. You've got to win games. It's plain and simple. What we're doing is not winning games, whether it's [because of] one aspect or another. We have to find the combination that does. I think we're all on the same page on that."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.