Gallen will start Friday in Game 1 of the World Series against the Rangers, Bob Nightengale of USA Today reports.
Gallen was available in relief but wasn't needed as the Diamondbacks disposed of the Phillies in Game 7 of the NLCS on Tuesday to advance to the World Series. He'll be pitching on five days' rest after taking a loss in each of his two NLCS outings. The Rangers have not yet named a Game 1 starter.