If Broncos QB Peyton Manning can marshal a drive during Thursday night's preseason opener at Chicago, he hopes it turns out better than the two-minute drill did at Tuesday's practice.

Manning and the first-team offense drove 56 yards to the 4-yard-line during the game-condition period of practice, but the drive petered out with four consecutive incompletions in a goal-to-go situation.

Although Manning wouldn't admit to frustration over his performance Tuesday, the series did offer an indication that the offense still has some hiccups as Manning and his new teammates adjust to each other.

"Every day, you're trying to get better. Certainly, there's always some things you can improve on," Manning said."

Typically, Broncos coach John Fox plays his starters for one possession of the preseason opener but will extend their stint to if there's a three-and-out or quick turnover on the opening series.

"When we're in there, we just like to put some kind of execution together out there. We'd like to get a drive or two going," Manning said.

Learning from mistakes: The two-minute drill period hasn't been kind to rookie QB Brock Osweiler the past two days with both of his series ending with INTs.  

Osweiler was the second QB up behind Manning in the two-minute drill Tuesday but saw his drive come to a quick end when he threw a pass behind WR Gerell Robinson that CB Tony Carter intercepted.

Even before reviewing the video of the play, Osweiler had sought to take a lesson from the mistake.

"That's a huge learning play for myself," Osweiler said. "We were in a situation where I had to throw hot. There were some free rushers coming off the edge, and that's a hard situation in the (shot)gun, because you've got to be able to get the football, try to get the laces and put an accurate ball out there quick."

Taking attendance: WR Demaryius Thomas saw some repetitions during the team period of practice but didn't take part in as many as usual because of an Achilles tendon issue that arose during Monday's practice. ... OT Ryan Harris sat out because of an ankle injury he suffered Monday. ... DT Ty Warren left practice because of a stomach problem. He appeared to have a case of the dry heaves early in the practice. Kevin Vickerson took his place on the first team.

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