Should I start Pierre Thomas or Matt Forte?

I had to start Justin Forsett cause he was playing the Rams so this leads to two backs. Luckily I have three hours to decide. Both backs have disappointed but I still need to play one of them. Forte is a reach but could put up some numbers if his crappy O-Line made some holes and the MNF game tomorrow should be a shootout and Pierre might join in on the fun.