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3/19/2014 7:59 P.M. ET

Red Sox have more to see from Sizemore

FORT MYERS, Fla. -- Grady Sizemore's progression continued on Wednesday when he went 3-for-4 with a double in a Minor League game. The center fielder is scheduled start Thursday night's home game against the Yankees.

The next two weeks will be critical for the Red Sox in determining whether Sizemore is physically able to break camp as the starting center fielder.

Sizemore has passed all tests so far, but there are a few more before the team can declare him the starting center fielder for Opening Day.

"We'll probably have a better read on that in another 10 days," manager John Farrell said. "Because next week, we're hopeful to have him play five times. There's been a pretty well thought-out plan to the increase in volume. We're going to take every available day to gather as much information."

Farrell projects that, following an off-day Friday, Sizemore will play three days in a row for the first time from Saturday to Monday.

"I didn't know how the body was going to hold up day to day, if I was going to be able to push it every day," Sizemore said. "So far it's allowed me to keep upping the volume and pushing the intensity. I still don't feel like I've reached that ceiling where I went too far. As long as I'm there, I'm happy."

The one thing Sizemore has not yet done is steal a base.

"We've put him in motion a couple of times already," Farrell said. "But to say we're just absolutely going to turn him loose with the green light ... we'll try to continue to ramp up his volume before we look to do anything situationally that might be different than what we've gone through right now."

There will come a time when the brakes come off completely.

"At a point in time in hopefully the near future, that all becomes 'react to the game,' and we've seen every other phase of his game be natural and second nature to him," Farrell said. "He's advanced on a ball in the dirt; we've put him in motion two or three times. There's no hesitation on him sliding or anything like that. So far, so good."

Sizemore is hoping his skills will continue to come back to him as the days evolve.

"Everything feels good, but I still feel like there's a lot of room for improvement -- getting breaks, getting a better first step, feeling more explosive, feeling that quickness in that good first step," Sizemore said. "I'm happy with where it's at, but I'd like a little bit more improvement."

Breslow nears spring debut with future in doubt

FORT MYERS, Fla. -- Lefty reliever Craig Breslow, an invaluable component to Boston's bullpen last season, will pitch in his first exhibition game on Monday. By then, the Red Sox should have a better indication of whether it is realistic for him to make the Opening Day roster with just one week of game activity in Florida.

Though the club has not linked a specific injury to Breslow, they said a conservative approach was observed to help avoid the fatigue that led to his starting 2013 on the disabled list.

"It's going to be dependent on what his needs are currently," manager John Farrell said. "To say we're following the same schedule or calendar we did a year ago, we're basing this all on what he's capable of. There's been no final determination yet. We expect him to be in a game on Monday. He's got a bullpen today and hitters Friday. We'll gradually get to the right decision."

The Red Sox have two other lefties in their bullpen in Andrew Miller and Chris Capuano. Farrell would not confirm whether, should Breslow start on the disabled list, he would replace him with another lefty.

"If there's a scenario in which he's going to be delayed, we'll look to take the best available pitcher," Farrell said. "And at that point, we'd like to think, or I personally think, that a multi-inning reliever is needed."

Worth noting

• Third baseman Will Middlebrooks returned to the lineup for Wednesday night's game after being bothered for several days by soreness in his right middle finger. The injury was never considered to be serious, and Middlebrooks hoped to keep building on what had been a solid spring so far.

"He went through a full day of activity yesterday, threw quite a bit, both in terms of his throwing program and taking ground balls," Farrell said. "He's back in tonight. We'll probably go tonight, and then both games on the road Friday and Saturday with him. We might take a look at [Jonathan] Herrera at third base a little bit more tomorrow night."

• Veteran catcher A.J. Pierzynski has always been an aggressive hitter, which contrasts slightly with Boston's organizational philosophy of working the count. But Farrell would not be surprised if just being around Boston's other hitters leads Pierzynski to alter his approach a little.

"He's had a long career of very good bat-to-ball ability, and because he can hit for a very good average, I think there's been a willingness on his part to be more aggressive in the count," Farrell said. "We've seen at-bats here where he's shown some tendencies to see a few more pitches. I know the conversation in the dugout from guys coming back that have that in their track record for a long time that continues to take place.

"And I think when you see our regular lineup repeatedly, I'm of the mindset that it will start to filter into his game somewhat. He'll see the benefits. I have to counter that with the fact we don't want him to change wholesale. We still want him to take advantage of his strengths, but I think he'll understand a little more readily when he sees guys building up pitch counts and grinding at-bats to get the starter out of the game a little earlier."

Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.