FLOWERY BRANCH — The Atlanta Falcons almost began the season without Jason Snelling. Now he could be one of the keys to the team's playoff hopes.

Most of Snelling's playing time in his five seasons in Atlanta has come at running back. Beginning with this week's game at Indianapolis, he has an opportunity to prove he can take over as the starter at fullback.

Pro Bowl fullback Ovie Mughelli's season-ending knee injury in Atlanta's win at Detroit on Oct. 23 leaves Snelling as the probable new starter.  Mughelli, who was placed on injured reserve last week, had surgery on Monday to repair a tear in his right MCL.

The Falcons signed fullback Mike Cox last week, but Snelling appears to be the first option to replace Mughelli. Snelling's normal dual role as a backup at running back and fullback will change as he focuses on blocking.

"As you know, Jason has been kind of that back who can play both," coach Mike Smith said after Monday's practice. "That's going to obviously change his role."

Snelling said he doesn't think the offense will have to change if he starts at fullback.

"I think we just pretty much call what we're going to call," Snelling said Monday, when the Falcons returned from their bye week. "I think my coaches have the confidence in me that I can go in there and get the job done and do what I need to do to help my team win."

Snelling talked with other teams, including St. Louis, as a free agent last summer before signing a one-year, $1 million deal to return to Atlanta.

"I just took the experience for what it was, free agency," he said. "I'm happy where I'm at. This is where I chose to come back to and I'm glad to be a Falcon."

Snelling rushed for more than 900 yards while backing up Michael Turner at running back the last two years. He set a career high with 613 yards rushing in 2009 and added 324 yards rushing last year.

The fifth-year back from Virginia has had only six carries for 24 yards this season. He has 12 catches for 89 yards.

Snelling likely will be the lead blocker for Turner against the Colts as the Falcons (4-3) look for their third straight win.

Snelling helped clear the way for Turner to rush for 122 yards in a 23-16 win over the Lions before the bye week.

"My career here has been as a guy who takes advantage of opportunities and a guy who can play different roles," Snelling said.

"They have that confidence in me and that's always good when your team has confidence you can do multiple roles. That was a critical time in the game that I had to go in there and step in. There was never a doubt from my coaches or my teammates that I could get it done, and we ended up getting the win. That was great."

With Snelling at fullback, rookie running back Jacquizz Rodgers could have more opportunities to run the ball.

"Whether Jason is at halfback or fullback, I think Jacquizz has shown he's got the skill set to be a running back in this league and we need to make sure we spread the ball around through the second half of the season," Smith said. "We've kind of been a little one-sided in our carries."

Turner has 621 of the Falcons' 789 yards rushing.

Snelling (5-11, 234) looks more like a running back than a fullback. He's lighter than Turner (5-10, 247).  Smith said Cox (6-0, 252) "is more of the body type of the traditional fullback."

"We're going to give him work to see what he can do and try to get him up to speed with our base offense," Smith said of Cox.

Cox, from Georgia Tech, played for Kansas City the past three seasons.  His younger brother Lucas Cox, also from Georgia Tech, was with the Falcons in training camp this year as an undrafted free agent and has helped with playbook questions.

"I was on the phone with him last night," said Mike Cox of his brother. "There were just a few little questions I had. He's definitely been a huge help."

NOTES: Rookie WR Julio Jones, who has missed two games with a hamstring injury, returned to practice. ... Smith said his coaching staff worked in the bye week on improving three areas: first down efficiency on offense, third-down defense and penalties. "We tried to analyze the areas we were getting the penalties and what the penalties were and why," he said.