Washington Redskins head coach Mike Shanahan said defensive lineman Albert Haynesworth will undergo an MRI on his left knee, Jason Reid of the Washington Post reports.

"We're giving him an MRI today because his knee has been a little bit sore, more sore than it has been in the past," Shanahan said. "In the past, every third or fourth day it'd be a little sore, according to the trainers. But now it's been a couple days consistently sore...We're going to MRI it, see if he's okay and then we'll go through the rehab work to get it stronger."

Haynesworth's knee prevented him from taking the team's conditioning test for a sixth straight day, which means the disruptive defender will miss a full week of full-squad practices. Haynesworth has been working with defensive coordinator Jim Haslett and defensive line coach Jacob Burney after practices, learning what his role in the team's 3-4 defense will be.

Reid reports those sessions continued on Thursday.

For more from Shanahan on Haynesworth, click here.