Stewart underwent an MRI Monday morning after exiting late in the first quarter of Sunday's win over the San Francisco 49ers. On Stewart's fifth and final carry of the game, his right leg briefly stuck in the turf after he was pushed back by 49ers cornerback Tramaine Brock.
With the Panthers again making Cameron Artis-Payne inactive in favor of others who play more special teams, Fozzy Whittaker filled in and smashed career-highs with 16 carries and 100 yards. Mike Tolbert added nine carries for 25 yards.
Despite Whittaker's success against San Francisco, don't expect him to take over Stewart's lead role against the Vikings. That will likely go to Artis-Payne.
"He's a stout inside runner," Rivera said. "He's more 'plant that leg and drive straight ahead,' where Fozzy is a little bit more niftier, a little bit better lateral movement."
"I have a tremendous amount of faith in who "CAP" can be for us. And knowing that you have a good change-of-pace guy in Fozzy, and you've got a guy that can come in and play situational football for you in Mike Tolbert - I think that's a good combination."
As a rookie, Artis-Payne was inactive for seven straight weeks until a foot injury shelved Stewart for the final three games of the regular season. Artis-Payne then had 38 touches compared to Whittaker's 21 and Tolbert's 20.
When asked if the Panthers planned to look at adding a back, Rivera said that would depend on the severity of Stewart's injury. For now, those who have wanted to see Artis-Payne in the lineup will get their wish.
"It has been a 'next man up' mentality that's been very beneficial for us over the last three seasons for us. And this is one of those circumstances," Rivera said. "If Jonathan's out for an extended period, we feel good about the combination of guys we have."
REPORT CARD VS. 49ERS
PASSING OFFENSE: A-minus -- QB Cam Newton's first pass was tipped and picked. Newton picked apart the 49ers from there. He threw four touchdown passes to bring his career total to 122, vaulting him past Jake Delhomme (120) for most in Panthers history. And Newton's 353 passing yards were his most yards since he went for 374 against the Bears on Oct. 3, 2011. WR Kelvin Benjamin dominated with two scores and TE Greg Olsen had career-best 78-yard touchdown reception.
RUSHING OFFENSE: A-minus -- RB Jonathan Stewart had just five carries before he left with a hamstring injury. Fozzy Whittaker then took over with 16 carries and 100 yards, smashing his previous career high (41 at Atlanta on 12/28/14). The Panthers totaled 176 rushing yards, extending their league-leading streak to 29 straight games with at least 100 yards on the ground.
PASS DEFENSE: B-minus -- The Panthers intercepted 49ers QB Blaine Gabbert twice, but he also tossed a pair of touchdown passes. The second went 75 yards to TE Vance McDonald, who somehow sprinted past Carolina's secondary. Gabbert was sacked twice and hit at least five other times.
RUSH DEFENSE: A -- The 49ers beat the Rams in Week One with a solid ground game, but they had no such luck on Sunday. The Panthers allowed just 65 yards on 26 carries, limiting RB Carlos Hyde to 34 yards on 14 attempts. A Hyde fumble was returned for a touchdown by LB Shaq Thompson.
SPECIAL TEAMS: B -- K Graham Gano bounced back from missing the game-winner in Denver by nailing all four of his field-goal attempts. But Gano had an extra point attempt blocked. P Andy Lee placed all three of his punts inside the 20. KR Ted Ginn Jr. muffed a kickoff, setting up the 49ers on the Panthers' 1-yard line. Ginn then went 59 yards into 49ers territory with his next chance.
COACHING: A-minus -- The Panthers were coming off a disappointing opening-night loss at Denver, but they had 10 days between games. The 49ers had just five, plus they had to travel cross-country. Coach Ron Rivera's team was ready to pounce on a team with inferior talent.