The Twins activated rookie outfielder Alex Kirilloff, who has never played above the Class AA level, for their playoff series against the Houston Astros because third baseman Josh Donaldson (calf) will be relegated to the taxi squad because of injury.
Kirilloff, 22, was the Twins' first-round choice (15th overall) in 2016.
"Alex Kirilloff is ready to play in the big leagues," manager Rocco Baldelli. "He's a guy who worries about the things that he can control, and that's it."
If Kirilloff plays, he'd be the third man in MLB history to make his debut in the postseason (Mark Kiger, A's, 2006; Adalberto Mondesi, Royals, 2015). He got a call in St. Paul from Baldelli on Monday night informing him of the promotion, and Baldelli said he was calm.
"Sometimes emotions don't match up with reactions," Kirilloff said. "I was excited for the opportunity. I stayed ready all summer. I stayed over at the Hyatt in St. Paul and walked to the ballpark every day."
Baldelli said Donaldson could only be used as a pinch hitter.
"We weren't going to be able to put him at third," Baldelli said. "So the question is, do we use him once a game as a pinch hitter? And if he comes out of the box at 75 percent and aggravates it? We're not willing to take a chance."
Should the Twins win the best-of-three series at Target Field, they would play in an American League Division Series at Dodgers Stadium starting on Monday.
Willians Astudillo is also on the roster, giving the team four catchers.
Lefty Rich Hill, who pitched Sunday, is not on the roster, but Jake Odorizzi and Randy Dobnak are.
Reliever Jorge Alcala, a former Astro, did not make the roster. To make room on the 40-man for Kirilloff, reliever Sean Poppen was designated for release or assignment.
Center fielder Byron Buxton, who had concussion like symptoms after being beaned on Friday, is in the lineup and hitting second behind Luis Arraez.
Lineups for today's 1 p.m. game (Ch. 5).
George Springer, CF
Jose Altuve, 2B
Michael Brantley, DH
Alex Bregman, 3B
Kyle Tucker, LF
Yuli Gurriel, 1B
Carlos Correa, SS
Josh Reddick, RF
Martin Maldonado, C
Luis Arraez, 2B
Byron Buxton, CF
Max Kepler, RF
Nelson Cruz, DH
Eddie Rosario, LF
Miguel Sano, 1B
Jorge Polanco, SS
Ryan Jeffers, C
Marwin Gonzalez, 3B
TWINS WILD CARD PLAYOFF ROSTER
Pitchers: Jose Berrios, Tyler Clippard, Randy Dobnak, Tyler Duffey, Kenta Maeda, Trevor May, Jake Odorizzi, Michael Pineda, Taylor Rogers, Sergio Romo, Cody Stashak, Caleb Thielbar, Matt Wisler.
Catchers: Willians Astudillo, Alex Avila, Mitch Garver, Ryan Jeffers.
Infielders: Ehire Adrianza, Luis Arraez, Marwin Gonzalez, Jorge Polanco, Miguel Sano.
Outfielders: Byron Buxton, Jake Cave, Max Kepler, Alex Kirilloff, Eddie Rosario.
Designated hitter: Nelson Cruz.
Taxi squad: P Jorge Alcala, IF Travis Blankenhorn, P Edwar Colina, 3B Josh Donaldson, P Jhoan Duran, P Rich Hill, PJuan Minaya, P Devin Smeltzer, P Lewis Thorpe, OF LaMonte Wade Jr.