Josh Donaldson will officially begin his rehab assignment with Class A Advanced Dunedin on Tuesday, per a tweet from Bob Nightengale of USA Today. The deadline to trade for a player and have him be eligible for the postseason is 11:59 p.m. ET on Friday.
Donaldson has been out of the Blue Jays' lineup since May with a strained left calf muscle. But if the veteran third baseman makes significant progress over the next few days, he could be placed on revocable trade waivers and join a playoff-bound roster before hitting free agency in the offseason. 
When a waiver claim is placed, the player's original club has three options:
• Work out a standard trade with the claiming club within 48 hours
• Allow the player -- and all money remaining on his contract -- to go to the claiming club with no return
• Pull the player back off waivers
Donaldson began ramping up the intensity of his workouts over the past week, increasing Toronto's chances of flipping the 32-year-old's $23 million salary to a postseason contender.
The three-time All-Star slashed .234/.333/.423 with five homers and a .757 OPS in 36 games prior to landing on the 60-day disabled list three months ago. Donaldson's locker was notably emptied on Sunday at Rogers Centre, and the third baseman attempted to clear the air with a statement.
"I want to play soon and wanted to make sure I have everything I need to do that," Donaldson said in the statement, which was issued through a club official. "So I asked the staff to pack my locker, then I can go through it."