Broncos coach Gary Kubiak knew what he was facing long before he stepped on the podium and looked out over the crowd of reporters Tuesday afternoon

“I know one of the questions,” he said, grinning. “But go ahead.”

After nearly two weeks of training camp practices, the Broncos’ quarterback competition among veteran Mark Sanchez, second-year player Trevor Siemian and rookie Paxton Lynch reached a significant marker in the race to be the starter. One had to be tabbed the starter for their preseason opener at Chicago on Thursday.

Sanchez, who practiced almost entirely with the first-team offense Tuesday, got the nod and is expected to play the first quarter. Siemian will take over in the second quarter, and the final two quarters will go to Lynch.

The order, while typically significant, takes on a different meaning for the Broncos this year as they transition away from the Peyton Manning-era and years of having a known starter to begin the season. But the starter for Thursday might not be the starter for Sept. 8, when the Broncos open their season with a Super Bowl rematch against Carolina. Sanchez and Siemian still are co-No. 1 quarterbacks on the Broncos’ first depth chart and have shared repetitions with the first team for the majority of the offseason.

The game is yet another test in a lengthy evaluation period for all three quarterbacks. At the top of the coaches’ checklist in deciding the season starter are the obvious: ball protection, consistency and sound decision-making.

“It’s live. That’s a part of (the evaluation) — what are you going to do with a live rush and how you adjust to that,” offensive coordinator Rick Dennison said. “And then games are just fast. We practice as fast as you can, but it’s a lot faster out there.”

Sanchez will receive time with the first-team offense Thursday, because reps for all starters will be limited. But the order of play is less important than the quality. In other words: Don’t read too much into which Sanchez starting the first preseason game.

“No, don’t,” Kubiak said. “What we’re going to do is put a number on reps and what we want to see from each one of them so that from an evaluation standpoint we’re looking at things pretty equally. That’s the most important thing.”