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6/6/2013 12:00 A.M. ET

Middlebrooks may stay in Minors to work on swing

BOSTON -- If Will Middlebrooks continues to swing the bat like he did Wednesday night in the second game of his Minor League rehab assignment, you can expect him to be back in Boston's starting lineup the first day he is eligible -- which is Saturday against the Angels.

Playing for Triple-A Pawtucket, Middlebrooks went 2-for-3 with a homer and five RBIs.

Earlier in the day, Red Sox manager John Farrell mentioned that the third baseman's rehab assignment could be longer than just four games.

The Red Sox want to make sure his swing is right before he returns to action.

In a meeting with Middlebrooks, Farrell emphasized some things beyond just proving he's healthy.

"[A chance] to get his timing back," Farrell said. "But then also let's use this as an opportunity to get a little momentum going before he comes back. We're hopeful that that is sooner rather than later. Saturday is still the day in which he's first eligible to be activated. It could very well be Saturday. It could be shortly thereafter."

The Red Sox have also been challenged against left-handed pitching this season. Entering Wednesday, they were tied for 20th in the Majors with a .241 average against lefties, while ranking first with a .288 average against righties. A healthy, productive Middlebrooks could add a dangerous threat against southpaws.

"I think the most important thing is our need for right-handed bats in this lineup to balance out our left side of the plate," Farrell said. "He's a vital part of that. We want to make sure he's got some momentum coming back to us with."

This sophomore season has been an inconsistent one for Middlebrooks. He is hitting .201 with eight homers and 21 RBIs.

"This isn't going to be based on batting average [at Triple-A]," said Farrell. "I think it's more important that as he was showing more consistently before the injury, the ability to drive the ball into right-center field. As we've talked many times over, that's when he's at his best. [He just needs] to take his normal, natural approach and repeat it. That's what we're looking for."

Meanwhile, Jose Iglesias has been holding down the fort at third base both offensively and defensively during the absence of Middlebrooks.

"I wouldn't say this is predicated just on what Jose is doing," said Farrell. "Bottom line is, I mentioned to Will, what's best for Will is best for us. And that's to get him in a position where he's swinging the bat good and he's feeling confident about himself. He's our third baseman. He will come back to us in that frame of mind and with that ability to swing the bat. We're going to be a better team because of that."

Ellsbury confident he can return Thursday

BOSTON -- While Wednesday marked the fifth consecutive game Jacoby Ellsbury missed with tightness in his left groin, the center fielder indicated to a club official that he's confident he will be in the lineup on Thursday night against the Rangers.

That would be good news for the Red Sox and Ellsbury. The leadoff man was just starting to get into a sustained groove before suffering his injury.

Ellsbury tweaked his groin in Philadelphia on May 30 while stealing a club-record five bases.

"Still unavailable tonight," Red Sox manager John Farrell said before Wednesday's game vs. Texas. "He went out and did some more ground base activities with running. We've got to get him to the point of being 80 percent or better intensity level before we can consider putting him back in the lineup.

"As we did with Shane [Victorino], we look at that eighth day of the 15 days as kind of a threshold to make a decision roster-wise. Right now, we're still not thinking about putting him on the DL, but if this continues, obviously we've got to get to that point."

Wednesday marked the sixth calendar day since Ellsbury sustained the injury.

Victorino set to open rehab stint at Pawtucket

BOSTON -- Shane Victorino's left hamstring strain has healed to the point that the Red Sox right fielder will begin a Minor League rehab assignment on Thursday for Triple-A Pawtucket.

"We're hopeful it's three to four games," said Red Sox manager John Farrell. "We're going to get a gradual progression as well. It will probably be five innings the first day. He will likely DH the second game, and then get back in right field in game 3."

Given how many nagging injuries Victorino has had of late, Farrell is going to make sure not to over-play him upon his return.

"We've already spoken to Shane about upon his return to us," said Farrell. "We've got to manage how many consecutive games he plays a little more diligently than previously. It wouldn't be uncommon to see him two on, one off for the short term."

The one thing that's clear is that Victorino made considerable progress over the last 24 hours.

"He wanted to go out [for his rehab] tonight," said Farrell. "He feels good right now. He ran aggressively. There's been no lingering effects today. His BP has been fine."

Farrell believes Biogenesis probe won't affect Sox

BOSTON -- Red Sox manager John Farrell doesn't think any of his players are involved in the investigation Major League Baseball is doing regarding performance-enhancing drugs purchased at the Biogenesis clinic in Miami.

Reports are rampant that Major League Baseball could be close to suspending up to 20 players, some of them high-profile.

"I'm confident, yes," said Farrell. "I know there's been some preliminary notice that none of our players are on it, but knowing them more first-hand as people, I certainly would be shocked if anybody does show up on it based on what we know about it."

Even if no Red Sox players are implicated, Farrell is still uneasy about what something like this does to the game.

"Well it's unfortunate that decisions are made as they've been," said Farrell. "Whether or not they're proven guilty remains to be seen. The one thing that's been so great about this game, whether it's this situation or whether it's been work stoppages, it's a resilient game and it's come back from the temporary black eyes that it has suffered, and I'm hopeful that this will be dealt with and resumed from this point forward in the same way."

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