• World Baseball Classic schedule, tickets
Roark, who was invited by Team USA before Scherzer's injury was announced, is coming off an excellent 2016 season in which he went 16-10 with a 2.83 ERA and led the Majors with nine scoreless starts of at least seven innings.
Roark will be making his first World Baseball Classic appearance, joining a rotation that already includes Chris Archer, Marcus Stroman and Danny Duffy, and could potentially feature Madison Bumgarner and Clayton Kershaw should Team USA advance to the later rounds.
David Price and Andrew Miller are two other star pitchers who could participate, but neither is confirmed yet.
Team USA opens play in Pool C against Colombia at 6 p.m. ET on Friday, March 10, at Marlins Park in Miami.
Matt Kelly is a reporter for MLB.com based in New York. Follow him on Twitter at @mattkellyMLB. This story was not subject to the approval of Major League Baseball or its clubs.