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OXNARD, Calif. -- Kellen Moore waited four years for a chance to prove he can be a solid backup quarterback in the NFL.

Four days into this training camp, his opportunity has turned to disappointment.

Moore had to be taken off the field on a cart late in Tuesday's practice. A source said the quarterback suffered a broken right fibula. It's unclear how long he'll be out.

The injury accelerates the rise of rookie Dak Prescott up the depth chart and sends the Cowboys scrambling to find a veteran replacement.

"We'll know a little bit more after we do some X-rays and things like that,'' owner Jerry Jones said, announcing the break as he walked off the practice field. "It's regrettable. We'll just basically take a look at it and address it from here.

"I don't have any comments about what, if anything, we'll be doing from here.''

Jones was adamant that Moore was the team's backup quarterback in his opening news conference last week, saying the club had no interest in veteran Nick Foles. That has obviously changed with Moore's injury.

Club officials were meeting Tuesday evening to discuss whether to pursue Foles or someone else. The Cowboys want to move quickly to ensure that the training camp plan it has in place for starter Tony Romo -- two days on, one day off -- can continue and to get the new quarterback up to speed in the system.

Video shot by Tyler TV station KLTV shows that defensive lineman Lawrence Okoye pushed left guard Jared Smith back into Moore during one of the final team drills of the day. Smith's left foot then appeared to step on Moore's right ankle.

"It'll be a tough loss for us, but somebody has to step up,'' said receiver Lucky Whitehead, who was on the field when the injury took place.

"Hopefully, we can get him back soon.''

Tight end Jason Witten has spoken several times in recent months about how good Moore has looked during the team's off-season program.

"Your heart hurts for him,'' Witten said. "He works really hard. He's constantly taking notes. He's studying. He's communicating.

"At that position, I've seen it with Tony for as long of a time as we came in. You never know when your [opportunity] is going to happen.

"He'll continue to fight. That's who he is, that's who he's been his whole life. He'll bounce back, I'm sure.''

The injury, at least for the moment, pushes Prescott up the depth chart to No. 2. The Cowboys' fourth-round pick became a starter in high school and college because the player in front of him was injured.

"I saw some guys come at his feet and him go down,'' Prescott said. "It always sucks when a guy gets hurt. You don't wish that upon anybody.

"I just have to come in each and every day and get better. That's all I'm worried about," Prescott said. "My main focus is just to come in and make sure these guys hold me accountable and I hold them accountable. Just be my best every practice.''

Offensive coordinator Scott Linehan and quarterback coach Wade Wilson have both commented about how good Prescott looks early in this camp.

"Honestly, his demeanor, his intelligence,'' Romo said Monday when asked what impressed him about the rookie quarterback. "He's a smart kid. He picks things up quickly. And for rookies that's not always the easiest thing.

"So I think that's been as impressive as anything, his ability to pick it up and then go do it.''

Witten added, "Dak is doing good. He's showing this stage is not too big for him.''

Head coach Jason Garrett said during last week's news conference that the team was excited by Moore's potential and "we're going to give him an opportunity.'' That's when Jones chimed in and declared Foles wasn't an option.

Why?

"We can't get him any snaps,'' Jones responded. "We've got four that are going to get snaps.''

That number is now down to three, which puts Foles and other veteran options into play.

Catch David Moore on The Ticket (KTCK-AM 1310 and 96.7 FM) with The Musers at 9:35 a.m. and The Hardline at 4:10 p .m. every Monday through Friday during training camp.

Twitter: @DavidMooreDMN

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