ENGLEWOOD, Colo. — Trevor Siemian took a big step Thursday — whether that's forward or back depends on how his sprained left heel responds to his first practice since getting hurt against Kansas City on Nov. 27.

"It was a positive day, so we'll see where we're at tomorrow," coach Gary Kubiak said after splitting snaps between Siemian and rookie Paxton Lynch at his first full practice of the week.

Kubiak characterized Siemian's practice as "very encouraging."

"We are where we thought we were going to be today," Kubiak said. "We didn't do much yesterday. Our expectations today were for him to take half of what was going on. He was able to do that."

Siemian moved around well during the 20-minute media access period and teammates later said he was sharp and mobile throughout the workout a day after he participated in a walkthrough.

In the locker room he walked with only the slightest hint of a limp.

"He's progressing the right way. It was a big test today. He had his orthotic in. So, we'll see how he comes in here tomorrow morning," Kubiak said. "Hopefully we'll keep moving forward."

The Broncos (8-4) visit the Tennessee Titans (6-6) this weekend.

Siemian sat out last week's 20-10 win at Jacksonville when Lynch completed 12 of 24 passes for 104 yards, but didn't turn the ball over in recording his first NFL win .

On Monday, Kubiak said his faith in his first-round draft pick out of Memphis hadn't been shaken, declaring Lynch has "a brilliant career ahead of him."

For now, he's a raw rookie learning a dense playbook, one who wasn't asked in college to make calls in the huddle, line up under centre or go through progressions as he does now.

Asked for his impressions of Lynch's second career start, offensive co-ordinator Rick Dennison said the troubles started in the second half when the Broncos "went deeper into the call sheet."

"That became something that he needs to work at a little bit more and he will. To me, the night before the game he was awesome. He went through every call and he knew his progressions very well. He knew what the problems were in each of our pass plays and where to get the ball on the run. He studied at it," Dennison said.

"That's my biggest takeaway is that he has really studied and was really working hard at it. He has made some strides; he just has some more strides to make."

Comparing quarterbacks' first three NFL games, Paxton's 79.2 passer rating is actually higher than a dozen active QBs who have made the Pro Bowl, including Tom Brady and Eli Manning. It's also better than Siemian's 74.4 rating in his first three games.

The Broncos have little room for error as they try to return to the playoffs to defend their Super Bowl title.

After this weekend, their remaining opponents are New England and Oakland at home sandwiched around a trip to Kansas City.

Siemian, even at somewhat less than 100 per cent, gives them many more options and versatility on offence.

But the Broncos won't risk it if he's not able to move around in the pocket to escape the kinds of hits that have sidelined him for 2 1/2 games this season.

"If you're going to send a guy out there, he has to be able to move around," Kubiak said. "He moved today in the things he did. Hopefully that's going to improve between now and game time. A good day today."

The addition of running back Justin Forsett this week should help keep the quarterback clean.

The ninth-year running back is adept in Kubiak's West Coast offence and one of his strength's is blitz pickup.

The Broncos lost Kapri Bibbs to a high ankle sprain last weekend and put in a claim for Forsett , who was waived by Detroit.

"He looks good," Kubiak said. "It's great to have him. He's a great kid. He knows exactly what's going on. I think he'll be able to help us this weekend. My expectations for him this weekend are to spell (Devontae Booker) and play. It's just really nice to get somebody who's up to the beat on what we're doing."

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