CHARLOTTE – Head coach Ron Rivera didn't sound optimistic Monday about running back Jonathan Stewart being able to play Sunday when the Minnesota Vikings come to town, but Rivera is optimistic about what the Panthers can do in the running game if Stewart misses time.

Stewart suffered a hamstring injury just nine minutes into Carolina's home opener Sunday. Fozzy Whittaker took over and gained an even 100 yards as the Panthers pulled away for a 46-27 victory over the 49ers.

"If it's a hamstring, which every indication points to that, it's going to be at least a week," Rivera said. "We'll see how severe. He said he felt pretty good walking around when I ran into him just a second ago.

"The one thing we've been able to do the last few years here is we've been able to replace guys when they're out. We've had a next-man-up mentality that's been very beneficial for us, and this is one of those circumstances. If Jonathan is out for an extended period, we feel good about the combination of guys we have."

In addition to Whittaker and fullback Mike Tolbert, the Panthers also would turn to Cameron Artis-Payne if Stewart is out – possibly as their lead back. Artis-Payne was inactive for the Panthers' first two games with nearly the entire roster healthy, a tough call that doesn't speak to what the coaching staff thinks of the second-year player.

"I've got a tremendous amount of faith in who CAP can be for us, and in knowing that you've got a good change-of-pace guy in Fozzy and a guy who can play situational football for you in Mike Tolbert," Rivera said. "CAP is a stout inside runner who runs the ball very well and has good vision. He makes good cuts, but he more plants the leg and drives straight ahead. Fozzy is more nifty, a little better lateral movement as you saw when he got outside, though he also ran inside a couple of times.

"They both have good hands out of the backfield. They both understand our protections and are good, stout pass blockers."

When Stewart missed the final three games of the 2015 regular season with a foot injury, Artis-Payne paced the running backs with 33 carries for 152 yards, while Tolbert and Whittaker combined for 115 yards on 24 carries. Quarterback Cam Newton was Carolina's leading rusher over the three games with 156 yards on 16 attempts.

The Vikings have running back concerns of their own. Adrian Peterson exited Minnesota's victory over the Green Bay Packers on Sunday night with a knee injury. His status for Sunday is uncertain.

Panther safety Dean Marlowe, who had been out six weeks with a hamstring injury, reinjured it in his return Sunday.

"It didn't sound good," Rivera said. "We'll see how he is."