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7/24/2014 5:45 P.M. ET

Ortiz day to day with back spasms after exiting late

TORONTO -- David Ortiz left Thursday's 8-0 loss to Toronto in the ninth inning with back spasms after he checked his swing on an offering from Blue Jays lefty Rob Rasmussen.

Ortiz came up clutching his back, and he was replaced by pinch-hitter Jonny Gomes.

Red Sox manager John Farrell said Ortiz felt a spasm in his mid-upper back, and he expects the slugger to be sidelined on a "day to day" basis.

"We're still examining him right now. Right now it's day to day," Farrell said.

Farrell said he's doesn't believe the Red Sox slugger has ever experienced a similar injury.

It was an unfortunate end to what had been a productive series for Ortiz, who went yard four times over four games.

In Monday's series opener, Ortiz swatted a pair of dingers -- his 452nd and 453rd -- to tie and pass Hall of Famer Carl Yastrzemski for No. 36 on the all-time home run list.

After going deep again Tuesday, he hit his 37th career homer at Rogers Centre on Wednesday, passing Alex Rodriguez for the most homers by a visiting batter at the stadium.

Ortiz has homered five times at Rogers Centre this year, tying his previous season high for home runs north of the border (2004, '05, '11).

Holt crosses final frontier with start at 2B

TORONTO -- Brock Holt became the first player in Red Sox history to start at every position outside of pitcher and catcher on Thursday.

After getting the day off on Wednesday, Holt was back in the leadoff spot and penciled in at second base as the Sox wrapped up a four-game series against the Blue Jays at Rogers Centre.

The 26-year-old's start at second was more about giving Dustin Pedroia the day off, manager John Farrell said, but there's no denying Holt's versatility gives the Red Sox a lot of flexibility. Still, Farrell said he has no plans to start Holt behind the plate any time soon.

"He's done a great job, there's no doubt," Farrell said. "We like to think that because of injuries, it's opened up and created some opportunities for him. If we had our choice, we would've liked to avoid all that. ... But in light of what's taken place this year, it's one of the better stories. [He's] a guy we can plan around in a number of ways as we go forward."

Before getting a breather Wednesday, Holt had played all 533 innings in the field since being recalled from Triple-A Pawtucket on May 17. Entering Thursday's series finale, he led the Majors in hits (77) in the 54 games he's played since taking the leadoff role on May 23.

Rehabbing Middlebrooks on fire at Pawtucket

TORONTO -- Will Middlebrooks homered on Wednesday in Triple-A Pawtucket's contest against Phillies affiliate Lehigh Valley.

Middlebrooks, who's on the 15-day disabled list with a fractured right index finger, continues to produce offensively since being sent on his rehab assignment on July 18.

The 25-year-old third baseman had hits in the last five games with the PawSox entering Thursday, going 8-for-19 with a pair of homers.

Red Sox manager John Farrell said Middlebrooks continues to improve, but the skipper couldn't provide a timeline for when he might be activated. Farrell said an adjustment might be necessary to get Middlebrooks back to the Red Sox.

With Stephen Drew, Xander Bogaerts and sometimes Brock Holt holding down the left side of the infield, it could be difficult to find Middlebrooks a spot in the lineup.

"We've communicated this clearly to Will," said Farrell. "He's very well aware of the need to get regular at-bats. We've got to do some things to maybe adjust the roster to accommodate that. Whether that happens naturally this upcoming week, that remains to be seen -- with roster adjustments or any potential trades.

"Before even saying anything about that, I'd be getting way too far ahead of myself. But more importantly, Will is healthy, swinging the bat well and playing daily."

Jamie Ross is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.