Trevor Ariza didn't play in 2nd half vs CLE because of a sore left knee. Ariza said he would "probably not" be available vs MIL #wizards— Michael Lee (@MrMichaelLee) March 13, 2013
It's not clear when Ariza suffered the injury. He last played at the 5:10 mark of the second quarter before being replaced by Martell Webster. Steve Buckhantz did note that Ariza was limping at one point, but he played through the pain at the time, so not much was made of it.
Ariza has played really well since returning from a hamstring injury in early January, so the Wizards would definitely miss him if he is sidelined for an extended period of time. But the team's success without Ariza in the fourth quarter gives some hope that they can survive. More time for Chris Singleton and Trevor Booker may not be a bad thing, and Webster can log heavier minutes in the short term.