It's the other side of the ball that's presenting a much larger set of issues.
Cutler suffered a groin tear in a 45-41 loss at Washington on Oct. 20, then attempted to return three weeks later before leaving with a high left ankle sprain in a 21-19 defeat to Detroit on Nov. 10.
McCown, who had not thrown a pass in the league since his first stint with Chicago during the 2011 season, has been more than serviceable in five games and three starts, completing 65.5 percent of his passes for 1,106 yards, seven touchdowns and one interception while posting a 100.8 rating.
The 34-year-old veteran will get his third straight start Sunday, though coach Marc Trestman is hopeful Cutler can return when the Bears host Dallas on Dec. 9.
"I'm confident. I think Jay is confident. You have to leave yourself an opening, but there is no underlying information here," Trestman said. "It's week to week with the understanding that at some point in time he'll be back."
The defense is trying to remain confident as well despite allowing a league-worst 145.2 yards per game on the ground. The Bears (6-5), who have allowed at least 40 points on three occasions for the first time since 1964, gave up 258 rushing yards in last week's 42-21 loss at St. Louis.
It marked the most they've given up since Peterson ran for 224 of Minnesota's 311 yards as a rookie in the Vikings' 34-31 victory Oct. 14, 2007.
"We're going to continue to work at it," Trestman said. "There are a lot of teams working in the same environment in the league. We're not going to give up on it. We're going to continue to press the issue. We're going to work harder on it this week and try to get better. We certainly have to. We know what we're up against this week."
Chicago's 14 rushing touchdowns allowed are the second-most in the league.
''We're never going to say we can't get the problem fixed, because it is fixable,'' defensive end Julius Peppers said. ''We're going to simplify it even more than it has been and we're going to keep continuing to work on it until it is fixed.''
Peterson ranks first in the NFL with 10 rushing touchdowns and second with 997 yards. He's averaged 120.6 yards in his last three against the Bears, including 100 on 26 carries in Chicago's 31-30 victory Sept. 15.
He ran for a season-best 146 yards while adding a touchdown in last week's 26-26 tie against Green Bay. Peterson may be in for another big performance with Chicago missing linebacker Lance Briggs and defensive back Charles Tillman.
"When you get hit with injuries, it tends to have an effect depending on the depth of your team," Vikings coach Leslie Frazier said. "They're going through what a lot of teams go through."
The Vikings (2-8-1) rushed for a season-best 232 yards last week, though they've struggled in plenty of other areas. They're giving up a league-worst 31.5 points per game and have forced only 14 turnovers.
Peterson took no consolation in last week's tie.
"It definitely wasn't celebration,'' Peterson said. ''It is what it is.''
Christian Ponder had one of his better performances of the season, though, finishing 21 of 30 for 233 yards and a touchdown. Frazier said Ponder, who threw for 227 yards with a TD and one interception in the first meeting with the Bears, will be back under center Sunday.
"The consistent play is what we're always looking for," Frazier said. "He had a good game, (now) put together another good game. There's no second-guessing about playing him. He earned it the way he played."
Minnesota will be getting its first look at McCown this season after Cutler hit tight end Martellus Bennett with a 16-yard touchdown pass with 10 seconds remaining to give the Bears the win in the first matchup.
McCown has benefited from the strong play of receivers Brandon Marshall and Alshon Jeffery, whose combined 1,805 yards are the most of any tandem in the league.
Marshall caught a season-high 10 passes for 117 yards and his ninth touchdown last week, going over 100 yards for the third time in four games.
Frazier said linebacker Erin Henderson will play Sunday despite his Nov. 19 arrest for drunken driving. He will not start against the Bears, who have won seven of eight against Minnesota.