TORONTO -- Marco Estrada suffered an unexpected setback in his return from a strained glute muscle when he was forced to leave Tuesday's rehab start with a blister on his right middle finger.
Estrada is technically considered day to day, but it's not immediately clear when he will be able to resume his rehab assignment with Triple-A Buffalo. The veteran right-hander was expected to rejoin the Blue Jays' rotation as early as this weekend in Chicago, but that no longer seems realistic.
The 35-year-old has been out since July 3 with the glute injury.

Estrada left Tuesday's start in the fourth inning after he allowed three runs on three hits and two walks while striking out three. Estrada surrendered a pair of home runs to Gabriel Guerrero and Josh VanMeter before leaving with one out in the fourth.
The latest setback is yet another blow to Estrada's potential value in the days leading up to the July 31 non-waiver Trade Deadline. Estrada was expected to be one of Toronto's top trade chips, but it now appears as though the Blue Jays will hold onto him and look to explore a possible move in August.
It's not immediately clear what the injury means for the future of the Blue Jays' rotation. Toronto went with a bullpen day on Monday, which would have been Estrada's day to pitch, and it's possible the club could look to do something similar for Sunday's series finale against the White Sox.
Toronto could instead opt to promote someone from the Minors with the top candidates being prospects Sean Reid-Foley and Thomas Pannone or a veteran like Nick Tepesch.
Right-hander Roberto Osuna also made an appearance in Buffalo's game against Triple-A Louisville on Tuesday afternoon. Osuna, who moved up from Class A Advanced Dunedin earlier in the day, allowed two hits and walked one but did not surrender a run while striking out one over one inning. Osuna is facing an Aug. 5 return date from a 75-game suspension handed down for violating the joint MLB-MLBPA Domestic Violence Policy.