As Mike Klis of The Denver Post reported on Wednesday, the Broncos put McGahee on IR. He can come back in the playoffs, but Manning will need to carry the team the rest of the season.
Wide receiver Demaryius Thomas is also battling an injury, so Manning has even less to work with.
With his team at 7-3 and in first place in the AFC West, the veteran quarterback has a chance to win the NFL Most Valuable Player award this season. He has been the biggest reason why his team is in position to run away with the division.
There have been no signs of lingering effects from his neck injury that kept him from playing last season.
The numbers are impressive. This season, Manning has put up (via ESPN.com) 2,975 passing yards, 24 touchdowns, seven interceptions and a 106.2 quarterback rating.
He is on pace to throw for more touchdowns and have a higher rating than he has in any season since his record-breaking 2004 campaign.
The 36-year-old is having arguably one of the most impressive seasons of his career. He has had to learn a new team's system, establish chemistry with receivers and rehab from multiple neck surgeries.
To do what he has done so far this season is spectacular. He has struggled against the top teams in the league, but he does not have to face tough competition down the stretch.
Denver has one of the easiest remaining schedules in the NFL, with games at Kansas City, against Tampa Bay, at Oakland, at Baltimore, against Cleveland and Kansas City. The Broncos could clinch the division in the next few weeks and easily end the season at 12-4.
The schedule is the biggest reason why Manning will continue to dominate opponents. The first five weeks of the season featured four teams in position to make the postseason.
He is already averaging nearly 300 passing yards per game and faces easier competition the rest of the way. His best game of the season came in Week 4 against the Oakland Raiders, and he will get another shot at them in a few weeks.
Manning is returning to form and looks like he is trying to prove something. He now has a defense that can help him advance in the playoffs, so expect him to go off in the final weeks of the season.
Not only will his team clinch the division early, but the quarterback will continue to put up impressive numbers on his way to a fifth MVP award.
If he continues to play this way, Manning and the Broncos could be looking at a first-round bye and a shorter road to the Super Bowl.
Losing McGahee makes it tougher on Manning, but he has shown throughout his career that he can carry a team into the postseason.