Brubaker will get the start in Friday's bullpen game against the Tigers, Susan Slusser of the San Francisco Chronicle reports.
The former starter has been used exclusively in relief this season by the Giants, though he has logged three-plus innings in five of his 34 appearances. Brubaker will be pitching on two days' rest after yielding one run in one inning of work in Tuesday's loss to the Rangers, so his pitch count is likely to be very limited.