GREEN BAY — James Jones' knee injury turned out to be more serious than the Green Bay Packers initially thought, and the No. 3 wide receiver could miss the Sept. 8 regular-season opener against the Minnesota Vikings at Lambeau Field.

Jones was believed to have suffered a bruise during the third quarter of Friday night's preseason victory at Denver, but further tests revealed a sprain, coach Mike McCarthy said after practice Sunday. Jones won't play in Thursday night's exhibition finale against Tennessee and is week to week, McCarthy said.

That means fourth and fifth receivers Ruvell Martin and rookie second-round pick Jordy Nelson will move up a notch and a sixth wideout could make the 53-man roster when final cuts are made on Aug. 30.

"Obviously, it gives me an opportunity, but you don't want to wish that on anyone. Hopefully James is back as soon as possible," said Nelson, who has five receptions for 48 yards in the preseason and was sporting 10 stitches on his chin — the result of a hit Friday night. "Hopefully, I can step in and do the best I can to fill in. I'm getting more and more comfortable every week and every game, so hopefully that continues."

Said Martin: "I really feel like I get opportunities all over the place. If this means that I play more, then obviously there's going to be more opportunities to come. But this is definitely a hit to our team. James makes a ton of plays when he goes out there. Whenever he's back and ready to go, then we'll roll from there. But if somebody goes down, we don't expect the group to drop off."

As for other players who missed Sunday's practice, McCarthy said linebacker A.J. Hawk (chest) and safety Atari Bigby (ankle) won't play Thursday, while cornerback Charles Woodson (knee bruise) is unlikely to play.

McCarthy said he was hopeful linebacker Brandon Chillar (lower back) will practice today and that defensive end Cullen Jenkins is "just kind of beat up right now" and may practice today. Defensive tackle Johnny Jolly aggravated a hip flexor injury and didn't practice Sunday.

Although defensive tackle Ryan Pickett "had a very good week last week," Pickett "was not able to pass the second day of testing" in order to practice, McCarthy said. "I'm hopeful he's going to be a late addition for this week."

Justin Harrell (back) received a second opinion from doctors in Charlotte, N.C., and McCarthy said the team "will hopefully have some more information here in the next day or so."

Nothing for Grant-ed

McCarthy wouldn't say how much starting halfback Ryan Grant (hamstring tightness) will play against the Titans, but following his first full-fledged practice since signing his contract extension, Grant said he's eager to get some game action after missing the first three exhibitions.

"However much I play, that's up to them. But I'm going to prepare like I'm playing the whole game," said Grant, who said he worked out for the training staff "for about an hour and change" inside the Don Hutson Center Saturday to show he was ready to return. "I just need to take advantage of every play that I do get, make sure that fundamentally I'm in it, my pad level is good, and just execute."

As for absorbing his first full-speed hit since the NFC Championship Game in January, Grant said, "I do want to get hit. A couple of guys on the team were laughing about it, saying the first play they're just going to let the whole defense just run (at me) and tackle me. I hope that doesn't happen, but I wouldn't mind getting hit."

Backup plan

McCarthy said he is "looking to possibly split" time between rookie backup quarterbacks Brian Brohm and Matt Flynn Thursday night after starter Aaron Rodgers plays his requisite series or two. Despite his struggles, Brohm will play before Flynn, McCarthy said.

"I need to get them as many reps as possible and give them some opportunities, not only in the run game, but also in the passing game," McCarthy said, adding that the Titans' tradition of giving their starters their most playing time in the finale will provide a good test for the two rookies. "I want them both to take a step forward."