Gallen (forearm) could return to start Tuesday's game against the Athletics, Steve Gilbert of MLB.com reports.
The Diamondbacks haven't yet determined a starter for Tuesday's matchup, but manager Torey Lovullo said that Gallen could end up starting the home game against Oakland. Gallen suffered a hairline fracture in his forearm late in camp but threw 67 pitches in an intrasquad game Wednesday and could be available for something close to his usual pitch count if he makes his season debut Tuesday.