ENGLEWOOD, Colo. – When the Broncos faced the Colts last season, all eyes were on Peyton Manning. He was greeted with a heartfelt tribute video upon his return to Indianapolis, making for an emotional night for No. 18.

While the Colts will forever be the team where he spent the first 14 years of his NFL career, Sunday night's matchup isn't about how Manning will fare against his former team. Sunday will be the first look at the Broncos post-Super Bowl XLVIII, debuting a team that looks vastly different than one last season.

The Broncos host the Colts on Sunday Night Football on NBC. During his press conference on Wednesday, Manning stressed the excitement that surrounds season openers.

"Regular-season season opener: It doesn't get much bigger than this aside from the postseason," Manning said. "I've always said opening day, opening night, is a playoff-type atmosphere. I am tired of talking; I am looking forward to playing some real football."

While the team looks very different from last season due to key personnel changes, a vital playmaker will also be missing for the Broncos as Wes Welker will miss the game due to a four-game suspension. But the Broncos offense is a well-oiled machine and this isn't the first time the team has had to deal with Welker's absence: He missed the last three and a half games of the 2013 regular season due to a concussion.

Manning noted that players like Jacob Tamme and Andre Caldwell filled in well for Welker during his absence last season, but he said it's more than the members of the offense and the pass catchers that need to "raise their level of play" during Welker's suspension.

"It's an opportunity for some certain receivers to get more playing time, whoever that is," Manning said. "We'll see. So it certainly is an opportunity [and] that's why you work in the offseason, that's why you throw to all your receivers in the offseason, that's why you go off-campus and have these off-campus mini camps at a private college, that's why you do it.

"For the starters, you do it more on the same page with them and for your new players and guys not necessarily starting to have excellent time with them as well. Hopefully that work will pay off for us."

The Broncos often reference the "next man up" mentality. But Manning said the responsibility of stepping up when players are out rests on the entire team. He said the correct way to think about it is a "next men up" mindset.

"It's kind of a plural thing, in this case a lot of people have to step up, raise their level of play," Manning said. "When you don't have one of your best players, a guy that's one of your top contributors, I think it falls on more than just one person. That's our challenge for DeMarcus Ware to play a little better on Sunday, for me to play a little better, for Montee [Ball], it falls on. I think everyone kind of points to the receivers; I think it falls on a lot of players on the team."

The Broncos have one of the toughest early schedules in the NFL this season, facing four teams who each had 10 wins or more last season. The Colts, who have made the playoffs the last two years, are expected to be tough AFC competition. Manning and the Broncos learned during last season's loss to the Colts that their defense is a tough, physical force.

Manning was sacked four times and picked off once and the Broncos racked up four turnovers. The Broncos were 5-of-16 on third downs during the 39-33 loss.

Welker's dynamic in the slot, specifically on third downs. Players like rookie Cody Latimer, Julius Thomas, Tamme and Caldwell will need to fill that role.

"I'd be lying to say this would be an easy transition and I think sometimes when you have some adversity, it's a challenge and sometimes your top players can really shine for you, can really step up and show you why they are top players and that's what I'm expecting out of certain guys," Manning said. "Third downs are going to play an important role in this game. These guys do a good job of getting you off the field on a third down. Last year they did and we expect them to be good in that category again this year."

"We pride ourselves in being a team that stays on the field on third downs. No matter who's in there, we expect everybody to be ready and it's our job to find a way to stay on the field, but there's no question it'll be a challenge."

The Broncos finished the 2013 season 95-of-205 on third down, good for the second-best third-down conversion rate in the NFL.

Manning said adversity like this requires the team to come together and for its members to feed off each other. While losing Welker for the first four games of the season will undoubtedly test the offense, Manning, who has been in this league for many years, looks at the positive when his team is dealing with a difficult situation.

He hopes that the team learned from last season's flurry of injuries and that they can succeed despite the struggles that are virtually unavoidable during an NFL season.

"Everybody else is talking about the negative going on," Manning said. "Right now we're talking about the positives—the football season being here and going out and doing our job. We have an opportunity, it's not going to be easy so I think all the veteran players fill that role and I guess I've always felt that way. It's when you find out a little bit about your team and can you handle it. It's easy when everything's going smooth and you don't have any types of adversity."

"There's no question it's a test so we'll see how we handle this test."