(UPDATE) According to Craig Sager, Brian Cashman says the Teixeira is headed for an MRI and does indeed have a hamstring injury. Cashman also said he will be petitioning MLB to add a replacement player to the roster, which would mean Tex is done for the remainder of the playoffs.
Mark Teixeira had to be helped off the field after running out a ground ball in the 5th inning of tonight's game. I'm no doctor, but it looks like we may have seen the last of Tex in 2010.
That freaking sucks.