HOUSTON -- The Astros left veteran relievers Will Smith and Phil Maton off their roster for the American League Division Series against the Seattle Mariners.

Smith, who was acquired from the Braves at the trade deadline, had a 3.27 ERA in 24 appearances for Houston this season. Maton had a 3.84 ERA in 67 games this season.

Instead of those veterans, the Astros put rookie right-hander Hunter Brown on a roster with 12 pitchers and carried an extra position player in rookie infielder David Hensley.

The rest of Houston's pitching roster is: Justin Verlander, Framber Valdez, Lance McCullers Jr., Luis Garcia, Jose Urquidy, Cristian Javier, Ryne Stanek, Ryan Pressly, Bryan Abreu, Rafael Montero and Hector Neris.

Brown, Hensley, Montero and Neris are making their playoff debuts, as are Houston rookie shortstop Jeremy Pena and utility player Trey Mancini, a six-year veteran acquired this summer after spending his entire career in Baltimore, and infielder Mauricio Dubon.

Houston will carry two catchers, eight infielders and four outfielders in this series.

The Mariners went with the same roster they did for the wild-card series. They will carry 12 pitchers, three catchers, five infielders, four outfielders, and utility players Adam Frazier and Dylan Moore.

Their pitching staff for this series comprises Logan Gilbert, Luis Castillo, Diego Castillo, Matthew Boyd, Matt Festa, Matt Brash, George Kirby, Andres Munoz, Penn Murfee, Robbie Ray, Paul Sewald and Erik Swanson.