TORONTO -- Josh Donaldson is expected to miss at least a few more days, and the Blue Jays don't seem to know exactly when he will return to the 25-man roster.
Donaldson has been out since May 28 because of a sore left calf muscle. There initially was some hope that the three-time All-Star would be able to return at some point during this weekend's series against the Nationals, but that no longer appears to be the case.
The Blue Jays put Donaldson through a series of running drills on Thursday afternoon, but he still wasn't comfortable running at full speed. He continues to take batting practice and field ground balls, but until Donaldson runs the bases without any issues, his availability will remain on hold.
"I was here watching him yesterday when he was running the bases, and he still couldn't cut it loose," Blue Jays manager John Gibbons said. "That's all I've got. He's feeling better, but he's still a little bit hesitant."

The injury has taken a lot longer to heal than the Blue Jays and Donaldson first anticipated. When Donaldson initially hit the DL on June 2, he said the plan was to return when the minimum 10-day requirement expired on June 8. The thinking was that Donaldson needed just a couple more days to recover, but he didn't want to leave the Blue Jays understaffed while everyone waited on his calf.
A four-game series against the Orioles and a three-game series against the Rays has passed since Donaldson was eligible to come off the DL. There is no set timetable on his return, and instead, the Blue Jays will wait and continue to evaluate Donaldson on a daily basis. Once cleared, Donaldson is expected to require a brief rehab assignment with Triple-A Buffalo.
"I think he needs to go down and at least play a game and test it," Gibbons said. "Game-like conditions. I think that would be smart."

Injury updates
• Right-hander Marcus Stroman will make a rehab start for New Hampshire on Monday. Stroman has been out since May 8 with what the club described as a period of mental and physical rest. He threw a simulated game at the club's Minor League complex in Dunedin, Fla., earlier this month, and then he began an official rehab stint with Class A Advanced Dunedin on June 13. Stroman allowed two runs on one hit and four walks over 4 1/3 innings in one start.
• Left fielder Steve Pearce will begin a rehab assignment with Buffalo on Saturday. He is expected to get the start at designated hitter, and it's not immediately clear when Pearce will return to the field for defensive duties. Pearce has been out since May 3 because of a strained oblique muscle.
McGuire changes teams
Right-hander William McGuire was claimed off waivers by the Rangers on Friday afternoon. McGuire was designated for assignment late last week to make room on the roster for right-hander Preston Guilmet. McGuire, who was a first-round Draft pick of the Blue Jays in 2010, made four appearances for Toronto this season, and he allowed six runs over 8 1/3 innings.