FOXBORO — The Packers are taking no chances with quarterback Aaron Rodgers, as Green Bay coach Mike McCarthy said Wednesday that Rodgers didn’t practice on Wednesday, probably wouldn’t practice on Thursday and added there was a “slim chance” for him to practice on Friday.

McCarthy added that a final decision on Rodgers will be “probably” be made on Saturday, “if he is cleared by the medical staff.” But first, Rodgers, who suffered a concussion earlier this season, will go through a series of tests, and McCarthy said he must be cleared by doctors before he can even take part in meetings or watch film.

“That’s a medical decision,” McCarthy said. “Dr. John Gray really controls the process of when they’re able to participate in meetings, and then obviously the next step from that is the physical conditioning, and then after that is the participation with the on-the-field activity. [Rodgers] was held out of meetings today.”

Despite the fact that this would almost certainly appear to put Rodgers behind the eight-ball when it comes to getting ready, McCarthy has faith in his starting quarterback, saying he played against Atlanta in his first year as a starter without practicing all week, “so we do have some history there.”

“He’s played a lot of football for us,” said McCarthy.

Rodgers is universally accorded as one of the finest young quarterbacks in the game, and his absence would almost certainly put Green Bay at a competitive disadvantage when it comes into Foxboro for Sunday’s game against the Patriots. In his sixth season with the Packers, the Cal product is ranked fourth in the NFL with a 98.5 passer rating, No. 8 with 3,289 passing yards, tied for sixth in the league with 23 touchdown passes and No. 3 in the league in passes of 25-plus yards with 32.

He’s faced the Patriots just once in his career when he came on in relief of Brett Favre in a 2006 contest between New England and Green Bay at Lambeau Field. It was his second season as a pro, and he was rough around the edges while completing 4-of-12 for 32 yards in a 35-0 Patriots’ win over the Packers.

“Rodgers has been very impressive,” said Patriots coach Bill Belichick. “Last time we played them, it was a different quarterback. This guy’s really come into his own and been as productive as anybody in the league.”

If Rodgers is unable to go, Green Bay will turn to backup Matt Flynn. A 25-year-old out of LSU, Flynn is in his second season as the No. 2 QB in Green Bay. He relieved Rodgers on four occasions last season and finished 7-for-12 for 58 yards and an interception. Last week against the Lions, he was 15-for-26 for 177 yards and an interception after Rodgers was knocked out of the game in the second quarter.

McCarthy was asked how much the passing game would change with Flynn at quarterback as opposed to Rodgers.

“It’s important for us to come to New England and be able to go against this defense. I think their defense is playing extremely well. I know that they’ve gotten better as the year has gone on. We’ve been very impressed,” McCarthy said. “It’s important for us to come [to] New England … We’re a quarterback-driven system, so it’s important for us to make Matt Flynn successful.

While Belichick acknowledges that things would be different with Flynn under center, he added that it doesn’t mean the Patriots should prepare for a radical overhaul of the Green Bay offense.

“I mean, their offense is still their offense,” Belichick said. “For them, [if] they change quarterbacks, it’s not like they have a hundred new plays that they haven’t run before just because they put one guy in there. They still run the plays that they run and I’m sure [Flynn’s] reads are still [the same] reads. You don’t have plays and have reads for this quarterback and reads for that quarterback or that type of thing. You run your offense [and] whichever quarterback is in there, executes it.

“Each guy has his own set of skills and it certainly is important to know who’s in there. But, at the same time, defensively, you are preparing for the same basic offense. The individual skills of the players within the offense, that may change, but you have to be aware of who they are and adjust accordingly.”