Skip Bayless and Stephen A. Smith agree that Sunday's Patriots-Cowboys game will be very ugly for Dallas. (1:31)

The Dallas Cowboys plan to use Matt Cassel as the backup to Brandon Weeden for the first time since trading for him, sources told ESPN's Ed Werder.

Cassel has had two weeks to learn the Cowboys' offense and said he feels comfortable being the backup against his former team when Dallas faces the New England Patriots on Sunday.

Kellen Moore drops to the No. 3 quarterback spot while Tony Romo is out with a broken collarbone.

Cassel began his NFL career as Tom Brady's backup in New England and won 10 games as a starter when Brady missed most of the 2008 season with a torn ACL