Utility infielder Brian Buscher was left off the playoff roster to accommodate the extra pitcher. Right-hander Jeff Manship, who made five starts during the 2009 season, also was not taken for the series against the Yankees.
"We have to keep the pitching, I just have to," manager Ron Gardenhire said. "With Duensing having to start today, this actually should be a three-pitcher series, but with [Scott] Baker having to pitch last night, I got to start Duens tonight.
"I actually wanted him in the bullpen and that would have helped me. I could have kept an extra position player. But I can't do that. It's just the way it is."
Nick Blackburn will follow Duensing to the mound as Friday's starter, but Gardenhire announced on Wednesday that Sunday's starter in Minnesota has yet to be determined. Carl Pavano was thought to have that spot, but with Baker being available on regular rest on that day, Gardenhire said the team would go with whoever was feeling better.
Closer Joe Nathan anchors the bullpen, joined by Francisco Liriano, Matt Guerrier, Jose Mijares, Jesse Crain, Ron Mahay, Jon Rauch and Bobby Keppel, who was the winner in Tuesday's thriller, but could have been left off if the Twins went with the extra position player. Gardenhire expressed no worries about the innings taking a toll on his relief crew.
"They're fine," Gardnehire said. "They are all fine. Every single one of them. I don't see any problems with anybody. This is the playoffs now. They have a day off tomorrow. They'll all be ready to go. By the time we get out, cool air, they'll be bouncing."
There also won't be any designated hitter days for AL batting champion Joe Mauer, as Gardenhire would do from time-to-time during the season to keep Mauer fresh. Mauer will be behind the plate for every game.
Alexi Casilla, Tuesday's hero, is part of the playoff roster, and the Twins took three catchers in Mauer, Mike Redmond and Jose Morales.