Toronto is expected to promote either Zach Stewart, Jesse Litsch or Brad Mills to fill the void that was created when Jo-Jo Reyes was designated for assignment late last week.
"The same names that we discussed earlier are still being discussed," Farrell said. "Jesse, Zach, Mills are the three. We don't anticipate Saturday's starter coming from outside the organization, at least at this point."
Litsch got the start on Monday night for Triple-A Las Vegas but didn't have much success. He allowed five runs on eight hits while striking out four in five-plus innings of work.
The 26-year-old is now 1-2 with a 8.16 ERA in six starts for the 51s this year. Despite the subpar numbers, it's still possible that he could rejoin the Major League roster.
Litsch was the Blue Jays' fifth starter until he sustained an impingement in his right shoulder and was placed on the 15-day disabled list on May 19. He then pitched at two different levels in the Minor Leagues during his rehab stint before settling in with Las Vegas.
"There were some inconsistencies as far as location," Farrell said of Monday's start. "Overall his stuff was the same as it has been. He had some good action with his sinker and his slider was what we've been accustomed to seeing.
"It falls on his fifth day and he is certainly a strong candidate for Saturday."
Stewart, meanwhile, made his last start on Friday for Double-A New Hampshire. He allowed just one run on six hits in 7 2/3 innings. The native of Texas would be required to start on seven days' rest if he got the call from Toronto.