In terms of attendance, the Broncos are having one of their most encouraging practices in weeks.

Defensive end Elvis Dumervil, back from his left shoulder strain, was not only practicing Friday, but he was also active. Linebacker D.J. Williams, back this week following his suspensions, was also participating full-bore.

The Broncos still must decide whether formally to add Williams to their roster by 2 p.m. Saturday. And Dumervil figures to be listed questionable when the team reveals its injury report later Friday.

But don’t be surprised if both play Sunday in the Broncos’ pivotal AFC West matchup with the San Diego Chargers at Sports Authority Field at Mile High.

Win, and the Broncos will have a three-game divisional lead against the Chargers, plus a tiebreaker that would essentially stretch their advantage to four games with six games remaining.

Lose, and the Broncos would have a one-game lead against the Chargers and no head-to-head tiebreaker.

Also practicing Friday — for the first time in two weeks — was cornerback Tracy Porter. It appeared Porter was only doing light work, but still he has been cleared by the Broncos’ medical staff to at least participate in non-contact football drills.

Porter has been battling symptoms that preceded the seizure he experienced in mid-August. While he has not suffered an epileptic episode since his seizure, symptoms of light-headedness and rapid heart rate, coupled with a brief trial-and-error period of finding the proper medication, have sidelined Porter since Oct. 14 — the day before the Broncos rallied to beat the Chargers 35-25 in San Diego.

Broncos right guard Chris Kuper also practiced as he has all week. Kuper missed the previous game at Carolina because of a severe left ankle sprain. It would be a surprise if he plays this week against the Chargers, although the following week’s game at Kansas City has become a stronger possibility.

Mike Klis: 303-954-1055, mklis@denverpost.com or twitter.com/mikeklis