Will a groin injury sideline Greg Jennings for Thursday’s game against the Bears? (Getty Images)

All signs would seem to point to WR Greg Jennings not playing against the Chicago Bears on Thursday night, although the Green Bay Packers listed him as doubtful for the game. 

Jennings took himself out of last Sunday’s loss to the 49ers on the final drive after suffering a groin injury, which has kept him out of practice this week. 

Still, there’s a sense the Packers’ top wide receiver will suit up and play against the Bears. 

ESPN Insider Adam Schefter said a league source told him Wednesday evening that Jennings playing on Thursday “sounds like 50-50 at this point.” According to NFL injury report designations, that would put Jennings closer to questionable than doubtful. 

Coach Mike McCarthy could have just ruled Jennings out at his press conference Wednesday afternoon. Instead, the coach said he hadn’t spoken to the 28-year-old receiver before meeting with the media and avoided saying Jennings wouldn’t play.

“They put him through everything,” McCarthy said. “Testing is a number of different drills and then his endurance through the drill. I’ll get the evaluation and then, frankly, [Thursday] will be the deciding factor.

"I think any time you’re dealing with veteran-established players, and definitely Greg Jennings is in that category, he’s played a lot of football for us. He’s played the whole time with myself as the coach. So the communication [Thursday], I trust the communication between Greg and the medical staff. So that’s when a decision will be made.”

Jennings, who was sidelined for two preseason games with a concussion, had five catches for 34 yards against San Francisco. But his absence would be a huge loss for the Packers because he plays all four of the receiver positions and is one of the offense's most reliable, consistent players. Jennings has averaged 1,108 yards and nine touchdowns over the last five seasons.

If he can’t go, more responsibility will fall on the other four wide receivers. Jordy Nelson and James Jones remain sideline deep threats, second-year playmaker Randall Cobb becomes even more important and veteran Donald Driver, who played only the game’s final three snaps last week, could see his role greatly expanded in the slot. Undrafted rookie Jarrett Boykin, who was inactive in Week 1, could even see some action if Jennings is out.

“It’s been consistent with the way we’ve approached the whole perimeter," McCarthy said. “We do things by concept. All of our receivers play all four positions so it’s something we’ll continue to do and move them around.”

Matthews appeals to rookies: OLB Clay Matthews had 2.5 sacks against the 49ers, his most in a game since 2010. But the fourth-year All-Pro knows he can’t do it by himself, especially on a defense that allowed 30 points last week and has struggled mightily since the beginning of last season. 

Green Bay spent its first six draft picks on defenders in April, and Matthews said those young players need to step up now, not later.

“We don’t have time for them to get acclimated," Matthews said Wednesday. “We need them to contribute right off the bat. Obviously, that was evident with [OLB] Nick Perry playing opposite of me, [DE] Jerel [Worthy] being in there, some of these younger guys. We’re going to need to have them continue to study and make sure they’re abreast of everything so that when they’re thrown into the game, it’s not as if they’re a rookie.”

If DE C.J. Wilson, who’s questionable with a groin injury, can’t play against the Bears, then Worthy, a second-round pick, could start in the base 3-4. Fourth-rounder Jerron McMillian will probably be the strong safety in the Packers’ oft-used nickel package, and Perry, the Packers’ first-round pick, is the starter at LOLB.

Starks progresses: Before Wednesday, when he jogged around and caught some passes with the other running backs, James Starks hadn’t practiced in more than a month since suffering a turf toe injury in the preseason opener. But McCarthy said he got “excellent news” about Starks on Wednesday morning.

“I was glad James was able to practice today and [I] had a chance to watch him practice,” McCarthy said. “That was something I wasn’t expecting. He’s making progress and looked good out there today. We’ll see how he feels [Thursday]. He’ll probably be part of the plan next week.”

Starks is listed as doubtful for Thursday’s game, and McCarthy said the only scenario where Starks would play against the Bears is if “something unforeseen happens.”

Practice squad moves: The Packers signed second-year CB Brandian Ross to their practice squad Wednesday, two days after releasing him to make room for reinstated OLB Erik Walden.

Ross had been on the 53-man roster when the season began, but as soon as Walden had served his one-game suspension for a 2011 offfield incident, he was back and Ross was out. 

Green Bay released undrafted rookie RB Marc Tyler (UCLA) to clear a spot on the eight-man practice squad for Ross, a 22-year-old who went undrafted last year and spent last season on the Packers’ practice squad.

Follow Packers reporter James Carlton on Twitter @CBSPackers.