Elaine Thompson, AP
Dallas Cowboys quarterback Tony Romo lies on the turf after he went down on a play against the Seattle Seahawks during the first half of a preseason NFL football game, Thursday, Aug. 25, 2016, in Seattle. (AP Photo/Elaine Thompson)

The Dallas Cowboys worst nightmare has been realized.

Pro Bowl quarterback Tony Romo has been sidelined indefinitely with a fractured bone his back.

Per sources, Romo is expected to be sidelined 6 to 10 weeks, though coach Jason Garrett refused to put a timetable on his return.

Garrett even declined to rule Romo out of the Sept. 11 season opener against the New York Giants because he has played with fractured bones in his back before.

“We’re going to monitor his condition day by day and we’ll see how he feels going forward,” Garrett said. “There’s no timeframe when he’s going to return.”

But that’s more wishful thinking as even Garrett acknowledged that the Cowboys expect Romo back “during the season”, making rookie fourth-round pick Dak Prescott the team’s opening day starter. Per a source, Romo’s most likely return is the Oct. 30 matchup against the Philadelphia Eagles, putting him out for the first six games of the season.

Romo suffered the injury on the third play of Thursday’s 27-17 preseason loss to the Seattle Seahawks when he was sacked by defensive end Cliff Avril.

He stayed on the ground for a few minutes in pain before walking off the field on his own power. The pain dissipated and Romo tried to lobby to go back in the game. Garrett kept him on the sidelines out of precaution.

After the game, the Cowboys and Romo thought they had dodged a bullet. He felt fine and seemingly hadn’t suffered a serious injury.

But he woke up Friday morning in discomfort as his back stiffened up on him, resulting in a magnetic resonance imaging exam. They learned of the fractured bone Friday night.

Garrett broke the news to the team after practice Saturday morning.

Romo, 36, has not played a full season since 2012. He underwent two back surgeries in 2013. He missed two games in 2014 with fractured bones in his back. He missed 12 games in 2015 after twice fracturing his collarbone.

The Cowboys will now turn to Prescott who has had a sensational preseason, completing 39 of 50 passes for 454 yards and five touchdowns with no interceptions. He has also rushed for two touchdowns. His quarterback rating of 137.8 in three games is the highest in the NFL.

Jameil Showers will now likely make the team as the third quarterback, serving as Prescott’s backup until Romo returns.

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