DENVER (AP) Peyton Manning is a backup for the first time since replacing an injured Todd Helton on Sept. 24, 1994, during his freshman year at Tennessee.
After standing on the sideline in street clothes or watching his longtime understudy on the big screen the last six weeks, Manning's left foot is healthy enough for him to play again.
But this is Brock Osweiler's team now.
''Obviously it means a lot,'' Osweiler said. ''It shows that coach believes in me.''
Osweiler has won four of his six starts, including in overtime against New England and Cincinnati. He insists he won't be looking over his shoulder Sunday and is only concerned with beating San Diego to secure a first-round bye, maybe even the top overall seed if Miami upsets New England.
A win by the Chargers would ease the sting of San Diego's worst season since 2003 and could send the Broncos tumbling into the wild-card round and a road game next week.
''If you need any extra motivation, shoot, in my mind it's, `Let's not let Denver play another game at home this year. Let's make this be their last home game,''' Philip Rivers said. ''We know obviously what the game means to them and what the atmosphere's going to be like. We're going to get a playoff-type atmosphere even though it'll be the end of it for us.''
Other story lines to keep an eye on Sunday when the Broncos try to wrap up their fifth consecutive AFC West crown:
MARSHALL PLAN: The No. 1 tackler on the league's No. 1 defense is dealing with a sprained right ankle and a heavy heart. Last week, Brandon Marshall attended the funeral of his best friend, Kaillon Brown, 27, who had cerebral palsy and died from complications of pneumonia.
''We knew he was sick but it kind of came out of the blue a little bit. I didn't get to talk to him or see him, which is kind of upsetting to me,'' Marshall said. ''I had bought a flight because I was going to see him, but actually I found out during the Raiders game (on Dec. 13) that he passed away. It was tough. I knew his condition was worsening. But I didn't think he would die at 27.''
Kubiak was reluctant to rest Marshall, a Pro Bowl alternate with 101 tackles: ''No, we're all in on San Diego,'' Kubiak said. ''We need to win this football game, so we'll approach it that way.''
BELIEF IN BRANDON: Broncos kicker Brandon McManus has missed kicks in each of the last five games, and astonishingly hooked a 45-yarder against the Bengals at the end of regulation Monday night before hitting a 37-yarder in overtime.
''It was a shock,'' special teams coordinator Joe DeCamillis said. ''But I'm glad everybody recovered from it.''
Kubiak insists his faith in his kicker is unshaken.
''We've got a lot of confidence in Brandon. I think he's had a fine year,'' Kubiak said. ''I know he didn't hit that ball well, but he comes right back and makes a big kick. He's going to have to make some more. That's part of his job ... He'll bounce back.''
CLOSING CHAPTERS: This will be the end of a miserable season for the Chargers, who haven't beaten a team with a winning record and have gone more than a year without beating an AFC West rival. Plus, ownership is trying to move to Los Angeles, and it could be the final game for embattled coach Mike McCoy.
''It's been a tough year to say the least,'' Rivers said, ''but we have a chance to go to Denver, hopefully win our first division game. Finishing the season with a win will send us into reloaded offseason mode in a decent mood.''
DIVISION DOUGHNUT: The Chargers are in danger of their first winless season in the AFC West since 1984 under Don Coryell.
Rivers is a big fan of San Diego and would hate to have to move to L.A., but he also loves Denver, where he's 6-4. He'd be 7-3, too, if not for Ed Hochuli's blown call on a Denver fumble in 2008.
FAREWELL FRIENDS: Wide receiver Malcom Floyd is playing his final game after 12 seasons with the Chargers, and tight end Antonio Gates' contract is up. Long-time safety Eric Weddle has already played his final game for the Bolts. He was put on season-ending IR with a groin injury. Weddle's contract is expiring and the team has made it clear he won't get an extension. His time with San Diego ended badly, as he was fined $10,000 for staying on the sideline at halftime of the Dec. 20 home finale to watch his daughter dance in a program sponsored by the team's cheerleaders.
AP NFL website: www.pro32.ap.org and www.twitter.com/AP-NFL
AP Sports Writer Bernie Wilson contributed.
Follow AP Pro Football Writer Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapleton