Yesterday was a painful day for the Orioles. In addition to being swept by the Rays and losing third baseman Manny Machado due to a scary leg injury, Alexi Casilla was forced to exit after he collided head-first into Nick Markakis‘ leg while attempting to make a diving catch in the seventh inning.
Casilla nearly made a remarkable catch on the play, but the ball popped out of his glove as a result of the collision. Despite laying on the ground for several moments and looking quite woozy, he finished the inning before leaving the game. According to Roch Kubatko of MASNSports.com, Casilla will undergo a CT scan to determine whether he has a concussion.
Casilla will have CT scan to see whether concussion. Was dizzy in dugout. Won't fly back with team
— Roch Kubatko (@masnRoch) September 23, 2013 
Source: D.J. Short, Hardball Talk