The Dallas Cowboys will start Brandon Weeden at quarterback against the Arizona Cardinals on Sunday with Tony Romo sidelined by a back injury, according to multiple reports.

Romo suffered two fractures in his transverse process – a small bone that sticks out of either side of the vertebrae – when he took a big hit during Monday night’s loss to the Washington Redskins, according to reports. He left the game, but later returned.

Romo did not practice all week and was officially listed as questionable for Sunday’s game. Weeden took all of the reps with the first team this week and will make his first start for the Cowboys, with rookie Dustin Vaughan set to be his backup. Weeden completed 4 of 6 passes for 69 yards and a touchdown while Romo was being evaluated during Monday’s game.

Romo’s injury is not the same as the one that required season-ending back surgery last year. The Cowboys leave for London and Monday in advance of next week’s game against the Jacksonville Jaguars, and then have a bye week. It is not known if Romo will travel with the team to London.