"Both corner outfields are kind of new for me," Sizemore said. "So I'm just going to try to get in as much work as I can early and just put yourself in a good position. It's one of those things where you make the adjustments, and I think if you can play outfield you can play. I think here more than anything it's just working the walls. Left field is a different situation, and right field's a little different. So just make sure you know how the ball's going to bounce and put yourself in a good spot."
This is not about finding out what Sizemore has to offer, said Red Sox manager John Farrell.
"I wouldn't say it's about taking different looks at him," Farrell said. "Mike Carp's swinging the bat well, Jackie [Bradley] has solidified defense in center field for us. So with Grady it's a matter of pushing him over and using his range a little bit more than Mike Carp's would be in right field.
"I wouldn't say that [Sizemore is] completely acclimated to left field yet. [Friday] was the first time he's played left field in Fenway Park. So there's still repetition needed. Yet at the same time, we feel like with his athleticism he should be able to play the corners with equal effectiveness."
It's also the first time Sizemore is playing in a day game after a night game this season, a reflection on his health status.
"Very good," Farrell said. "He's responded well. There's been days when he's had an off-day where he felt like he could continue on, so all those are positive signs."
Sizemore, who joined the Sox as a free agent in January, said bouncing between the outfield spots is not difficult, despite his lack of experience in the corners.
"It's fine," he said. "[The mental] aspect is not really an issue. I kind of knew coming into the situation [with the Red Sox] that I was probably going to be used in multiple spots, so I kind of prepared for that this spring and I told them I'd be ready no matter where you put me."
Fenway Park's right field can be intimidating, though, especially in a day game with the sun.
"You can get as much work as you can get, but you still got to get game action," Sizemore said. "It's completely different. So just get in the right spot and try to just be on your toes, get good jumps and put yourself in the right position."
Sizemore didn't play right in a Spring Training game, but he did get some work there during camp.
"I think I took reps as much as I can early on in camp," he said. "And when the season starts kind of just go to your position on that day. I'll be fine."
Regular right fielder Shane Victorino, who's on the disabled list with a right hamstring strain, is starting a rehab assignment with Triple-A Pawtucket on Saturday. Sizemore said he didn't have a chance to discuss with Victorino the quirks and crannies of Fenway's right field.
"Not really," Sizemore said. "But we did all this work in Spring Training. The dimensions are the same, so it's just a matter of putting those reps into the game."