ENGLEWOOD, Colo. --The day-to-day rotation of quarterbacks Trevor Siemian and Paxton Lynch will continue in the first two preseason games.

Head Coach Vance Joseph announced after Monday's practice that Siemian would start the preseason opener at Chicago on Thursday, with Lynch starting the second preseason game against the San Francisco 49ers on August 19.

Siemian and Lynch were listed as co-No. 1 quarterbacks on the first depth chart of the season issued Monday morning.

Siemian led the No. 1 offense for the first team-period repetitions of OTAs and training camp, so in that regard, Joseph's decision was no surprise.

"He's been first out all spring and all training camp. I think Trevor's earned that much, to be the first guy out," Joseph said.

That does not mean that Siemian is in the lead in the ongoing competition, Joseph said.

"No, no, no, no," Joseph said. "He's first out. He's been first out all training camp. It's an open competition. The games matter. The games start Thursday."

"I want to get to the games so we can get to the bottom of this."

Joseph said he was uncertain how much each quarterback would play against the Bears, but "it's going to be more than most starting quarterbacks would play the first couple of weeks."

Some first-teamers will stay in the game after he inserts Lynch for Siemian on Thursday "just to keep the offense intact so the guy can play his best," Joseph added.