Harrison (back) threw 78 pitches over five innings in a rehab start with Triple-A Round Rock on Wednesday, Stefan Stevenson of the Fort Worth Star-Telegram reports. He gave up two earned runs on five hits and posted a 4:1 K:BB ratio in the game. Harrison has advanced to game action after throwing several times at the Rangers' extended spring training complex. With him already extending his pitch count to around 80 pitches, he could rejoin the big club at some point in the next few weeks.