Gentry left midway through Tuesday's game after colliding with White Sox second baseman Carlos Sanchez, possibly suffering a head injury, USA Today's Bob Nightengale reports. He walked off under his own power but looked shaken up. It's possible he just got the wind knocked out of him, but his head may have collided with Sanchez's shoulder, so a concussion is also possible. Consider him day-to-day for now, and we'll update his status when the A's specify on Gentry's injury.