Because the Twins had Monday off, Liriano will be starting on his usual four days' rest.
"It's his fifth day" Gardenhire said of Liriano. "It wasn't planned this way, but with Perkins sick, we'll have Liriano go tomorrow and then we'll go from there."
It's still unclear just when Perkins will be able to make his next start. The left-hander could be slotted in for Friday's series opener against the White Sox, but that will all depend on his health.
Should the pitcher's flu-like symptoms linger, his start could be pushed into the weekend, with some of the other starters being moved up as well.
Currently, Nick Blackburn is scheduled to start Saturday's contest against the White Sox, but Gardenhire said on Wednesday night that Blackburn is a possibility to start on Friday.
"All of the guys could go on their fifth day if they have to," Gardenhire said. "Perk could go Saturday as well. We'll just go day by day and see how he is over the next couple of days."
Gardenhire first received news of Perkins' illness when he arrived at the Metrodome around noon CT on Wednesday.
Perkins had contacted the Twins training staff earlier in the day and mentioned that he had a fever and was feeling sick. Gardenhire said the lefty wanted to try to get up and come to the ballpark, but Perkins then called back a short time later to say he was still feeling ill.
Gardenhire then called Swarzak and informed him that the righty would be making his sixth career start later that night in Perkins' place.
Moving Swarzak's start up a day didn't put him on short rest, as he hadn't pitched in 10 days. The right-hander last started for Triple-A Rochester on June 28, when he allowed one earned run over seven innings.
"I think he's fine," Gardenhire said of Swarzak starting on short notice. "He's been waiting to pitch for about a week now. He's had plenty of time to prepare himself. He's excited to be back up here, and he's ready to pitch."
Swarzak pitched 4 1/3 innings against the Yankees on Wednesday night, giving up four runs on eight hits in defeat.