Arizona Cardinals running back Rashard Mendenhall exited last night’s third preseason contest due to a right knee injury, according to Darren Urban of AzCardinals.com.

At this point, the extent of Mendenhall’s injury isn’t clear. The back was deemed questionable to return to the game, and Urban reported that he later saw Mendenhall walking around on the Cardinals’ sidelines.

Prior to suffering the injury, Mendenhall had a good showing during the team’s most pivotal preseason game. He finished the contest with 47 yards on six carries, showing signs of why he was taken in the first round by the Pittsburgh Steelers.

However, by exiting with his knee injury, he showed why the Steelers decided to let him walk this offseason. Mendenhall has been hampered by injuries throughout his career, and he’s dealt with tendinitis in his right knee during training camp.

Considering Mendenhall was seen walking around following his exit, it’s unlikely that his knee injury is serious. Arizona could elect to sideline him as a precaution through the remainder of the preseason, but it doesn’t look like this will endanger his start to the regular season. Still, people figure to keep a closer-than-usual eye on Mendenhall, considering his injury history.