CENTENNIAL, Colo. -- The quarterback derby lost mystery weeks ago. Trevor Siemian pulled into the lead, teased Paxton Lynch supporters last week, then delivered the knockout punch in Saturday's 33-14 victory over the San Francisco 49ers.

Far more intrigue remains on the offensive line. Entering the third and most important preseason game this Saturday at home against the Packers, the left guard spot is up for grabs. Veteran Allen Barbre is pushing to unseat Max Garcia. Coach Vance Joseph said there are no plans to move Ronald Leary to left guard. He will stay on the right side next to tackle Menelik Watson. It leaves the offensive line closer to taking shape.

"Those guys have brought an edge," Siemian said.

Garett Bolles, who was flagged for four penalties last weekend, opens Sept. 11 against the Los Angeles Chargers at left tackle. Matt Paradis starts at center this week, making his exhibition debut. If he shows he has returned to form following offseason hip surgeries, he anchors the middle. If he needs more time to recover, then Connor McGovern would take the spot. McGovern has turned heads over the last month.

Charles in charge

Jamaal Charles continues to get healthy. He insists his confidence is high. For the first time arguably in his career, he will play in a huge preseason game. Charles receives one chance to make the team. The former Kansas City star will receive an extended look in an opportunity this Saturday to secure a roster spot in a room crowded with contenders De'Angelo Henderson, who appears to have made the team, Stevan Ridley and Juwan Thompson.

Charles must show he can contribute early in the season, perhaps as a third down back. Otherwise, the Broncos will be hard-pressed to guarantee his roughly $1.5 million salary if he's on the team on opening night. There are no plans to play Charles in the final exhibition game. Makes me wonder if Charles doesn't show up well Saturday, if Denver would release him to give the veteran a better chance to stick elsewhere.

Footnotes

Former Northern Colorado star Kyle Sloter receive a cold dose of reality Monday. Joseph said there are no plans to keep three quarterbacks on the roster. Chad Kelly has long been expected to start the season on the injured reserve. Sloter sets up as a potential practice squader, either here or with another team, after enjoying a strong camp. ... Rookie receiver Carlos Henderson has a cast on his hand following surgery. He is a candidate to begin the season on the IR. ... The Broncos waived veteran Bernard Pierce and claimed Cincinnati running back Stanley Williams off waivers.