Denver Broncos to start Mark Sanchez on Thursday

ENGLEWOOD, Colo. -- The Denver Broncos don't know who their starting quarterback will be for the regular-season opener.

But for the preseason opener, it's Mark Sanchez.

Although Broncos head coach Gary Kubiak listed Sanchez and second-year passer Trevor Siemian as co-No. 1 quarterbacks on the depth chart that was issued to the media Monday, the team announced one day later that Sanchez would start and play the first quarter in Chicago, with Siemian working the second quarter.

Rookie Paxton Lynch, the No. 3 quarterback on the depth chart, will play the entire second half -- which means he will see the most snaps of any of the quarterbacks.

Whether that continues for the rest of the preseason could depend on how well Lynch plays. Through his ups and downs as he learns the offense and how to operate under center and in a huddle, the question of whether Lynch can do more in the free-flowing game-day environment has existed.

Lynch's feel for a collapsing pocket and his willingness to step up and use his feet to buy time and to give his receivers time to break open downfield is a significant part of why the Broncos took him in the first round. But these are also the traits that are least likely to manifest themselves in practice.

So Lynch has consciously tried to focus less on remaining in the pocket during practice and more on escaping when he feels the rush in the last few days.

"If something's not there the first, second, or third read, and I feel the pocket breaking down, I'll get out and run with it like you would in the game," he said. "That's kind of how I see those reps, when it's in the game and the pocket breaks down, I'm going to run with it in practice."

It's helped him continue to pull his game together. Sacks have become more rare, and his confidence and resilience appear to be rising, evidenced by a 14-of-17 stretch Tuesday that followed an interception on his first pass.

What the Broncos want to see from Lynch is consistency and good decision-making. He has become more accurate on deep passes and looks more comfortable working under center and in executing the play-action bootleg that has been an integral part of Kubiak's offenses dating back to the 1990s and the final years of John Elway's playing career.

But they want to see that from Sanchez and Siemian, as well. Sanchez threw one pick-six in each of the Saturday and Monday practices. Siemian has shown a greater willingness to test the defense deep, but also struggled under heavy pressure during a two-minute period Monday.

There are still plenty of questions. What Kubiak hopes to see Thursday are some answers.