49ers’ Brock Purdy will start vs. Bills, Bosa, Williams, Banks and Lenoir are out

SANTA CLARA — It’s not like he was throwing at game speed, but the sight of Brock Purdy throwing the ball during warmups Friday was encouraging before the 49ers left on a trip to Buffalo for a Sunday night game against the Bills.

It was even more encouraging following practice, when Purdy was listed as questionable with a shoulder injury but declared the starter by coach Kyle Shanahan to face the Bills.

“I feel good, so I’m excited to be able to play,” Purdy said before the 49ers left for Buffalo.

As for Purdy’s supporting cast, it will be without some key players. The 49ers will be missing the left side of their starting offensive line as tackle Trent Williams (ankle) and guard Aaron Banks (concussion) are out and will not make the trip.

It was the second straight missed game for Williams, who will be placed by Jaylon Moore. While coach Kyle Shanahan declined to name a starting left guard, both Purdy and tight end George Kittle said Ben Bartch would step into the lineup.

Defensively, two of the 49ers’ best players this season are out and will not travel as defensive end Nick Bosa (obliques, hips) and cornerback Deommodore Lenoir (knee) won’t play. Defensive tackle Jordan Elliott (concussion) also will be sidelined.

While Lenoir won’t play, cornerback Charvarius Ward will be active and could start, missing three games on bereavement after the death of his 23-month-old daughter.

It was the first time Purdy had thrown in the presence of reporters since he was listed with a sore shoulder coming out of a Nov. 17 loss to Seattle.

Purdy was also listed as limited Thursday during a closed practice, a day in which he said he made considerable progress and was throwing without pain.

In open media periods since the injury, Purdy has done footwork and handoffs but not thrown the ball other than a few lobs to assistant coaches and the support staff.

.Check back for injury report updates…