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7/4/2014 7:20 P.M. ET

MRI reveals tear in Blanks' left calf

OAKLAND -- An MRI has revealed a slight tear in Kyle Blanks' left calf, meaning he will be on the disabled list longer than originally expected.

"He's going to be a while," manager Bob Melvin said Friday. "There is a little bit more of a strain going on in the calf, a slight tear. He's going to be considerably longer than we were originally thinking."

Blanks had been playing with a left calf strain, but he was forced to go on the 15-day DL when he aggravated it during a June 22 game against the Red Sox. He had recently begun taking swings, but in light of the MRI results, Melvin said there is no timetable for his return.

Since being traded to the A's from San Diego on May 15, Blanks is 15-for-45 (.333) with two home runs and a .446 on-base percentage. He has appeared in 20 games at first base in addition to a couple of corner outfield appearances.

The setback for Blanks could mean an extended opportunity for first baseman Nate Freiman, whom the A's recalled Sunday after Josh Reddick (right knee strain) returned to the DL.

Moss exits with sprained left ankle

OAKLAND -- First baseman Brandon Moss left Friday afternoon's game against the Blue Jays after the eighth inning with a sprained left ankle.

Moss grounded into a double play to end the eighth, and he never got out of the batter's box, falling to the ground after twisting the ankle in an attempt to begin running to first base.

Alberto Callaspo replaced Moss at first base in the ninth inning.

"I just rolled it, and when I rolled it my feet came out from under me," Moss said after the game, which the A's won, 1-0, in 12 innings. "Then I tried to get up to run to first, and when I stood up to run it still hurt."

Moss was initially concerned that the injury could be serious, but the pain quickly subsided.

"When I first did it, I thought I had done something to it pretty bad, but when I walked on it, it didn't hurt nearly as bad as I thought it was going to," Moss said.

Moss and manager Bob Melvin said that they will wait to see how the ankle responds Saturday to determine whether Moss will need to miss any time.

Donaldson back in lineup after two days' rest

OAKLAND -- Josh Donaldson was batting fifth and playing third base against the Blue Jays on Friday after missing the previous two games due to back stiffness.

Manager Bob Melvin said Donaldson felt good after taking batting practice in the cage Friday morning.

"I just wanted to talk to him before and see how he feels this morning," said Melvin. "There's no issues."

Donaldson has started all but five of Oakland's 86 games this season, and while Melvin is certainly happy to have his slugger healthy, he thought Donaldson could benefit from some rest before the All-Star break, anyway.

"We have quite a few guys that have been out there a little bit more than I'm comfortable with," Melvin said. "It's nice to be able to give some guys some days off, especially with the [upcoming] stretch."

Donaldson has 18 home runs and 61 RBIs, putting him on pace to shatter his 2013 totals of 24 homers and 93 RBIs.

Worth noting

• Melvin said he spoke with crew chief Bill Miller Friday morning about the bizarre replay situation on Thursday that led the A's to play the game under protest.

"He explained to me what the thought process was. I appreciate that," Melvin said. "I think it was probably a no-win for anybody at the time."

• Reddick has started doing cardio work in the weight room as he begins another rehab on his right knee, but he has not yet begun baseball activities.

• Catcher Derek Norris has slightly adjusted his positioning behind home plate, Melvin said, moving back a bit in hopes of avoiding hitters' backswings.

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