Packers running back Brandon Saine, who was injured covering a kickoff in the win over the Houston Texans on Sunday night, has been placed on injured reserve and will miss the rest of the season. (US Presswire)

The season is over for Packers linebacker D.J. Smith. That was the biggest news out of Green Bay on Monday, when coach Mike McCarthy addressed the media one day after his team’s biggest win of the season, a 42-24 triumph at Houston.

McCarthy didn’t provide specifics, but after the game Sunday night he said Smith had suffered a “significant” knee injury. On Monday, the team announced RB Brandon Saine had been placed on injured reserve, ending his season with a right knee injury as well. Saine was hurt covering a kickoff. The Packers claimed RB Johnny White off waivers from Buffalo to take Saine's place on the roster.

Smith was injured on an eyebrow-raising play when Texans LT Duane Brown blocked him from the side, causing Smith’s knee to twist and buckle, sending him to the ground in a heap. McCarthy was asked if he thought it was a dirty hit.

“It’s something you obviously don’t want to see happen,” he said. “It probably depends on which side you coach. I think Brown was probably trying to finish the play. It was an ugly play. D.J. suffered a serious injury.”

Smith, a second-year tackling machine out of Appalachian State, was the replacement for Desmond Bishop , who’d been placed on IR in training camp with a hamstring injury. While the Packers aren’t exactly thin at the position -- they have four ILBs behind Smith -- there is a significant drop-off in talent and understanding of the defense.

Smith, who finished the season with 35 tackles in a little more than five games, had many responsibilities. He was one of the two linebackers in the Packers’ nickel defense and the only linebacker in their dime package. The options to replace him include the young, unproven and unremarkable.

Versatile veteran Brad Jones, who played OLB his first three seasons before moving inside this year, took Smith’s place against the Texans. He made two tackles, including one for loss when he stopped Texans RB Arian Foster for minus-one yard just before halftime.

“I thought he played well,” McCarthy said. “There are a couple things he’ll learn from."

If Jones falters or can’t get the job done, Green Bay could look to one of three special teams stalwarts. Rob Francois, a smart, quick-study veteran with decent cover ability, is the backup at strong ILB behind A.J. Hawk. He’s been a monster on special teams, making two impressive, punishing tackles on kickoffs against Houston. Undrafted second-year Jamari Lattimore, an OLB last season who bulked up to shift inside, had a strong preseason and could be an option. Or rookie fifth-rounder Terrell Manning, who had a quiet camp, could become the best fit, given that ILB is his natural position.

“Obviously Rob and Brad and Jamari have a lot of special-teams responsibility,” McCarthy said, wary of moving a special teams player onto the defense.

McCarthy said he likes Manning, who’s been inactive five of six games this season. “I think he’s doing a good job and I like him on special teams,” McCarthy said. “That’s where he has pushed to play. I think he’s farther ahead on special teams than he is on defense.”

More injury news: While the news on Smith and Saine was as bad as feared, the report on OLB Nick Perry was better than expected.

“I saw Nick today, he looks good,” McCarthy said. “I haven’t really had a chance to talk to (team doctor) Pat McKenzie about it. It’s better than we thought it would be. I had a chance to see the play on the Jumbotron; it was very awkward the way he fell.

“I think we were very fortunate.”

McCarthy said he’d have more information on Wednesday about Perry, who left in the second quarter but was walking and laughing on the sideline, and CB Sam Shields, who left the game with a shin injury.

Green’s the man: Second-year RB Alex Green, getting his first career start in place of veteran Cedric Benson, apparently played well enough against the Texans to win the job.

Green rushed 22 times for 65 yards, with a long gain of 10. He also caught one pass for eight yards. He proved enough of a threat to keep Houston’s defense honest and provide needed balance to the Packers offense.

“I was very pleased with Alex Green,” McCarthy said Monday. “He’ll be our lead running back as we move forward.”

McCarthy added that Green, who was eased into the offense slowly in camp after returning from an ACL injury suffered midway through last season, is “past the rep count” he’d been on in the preseason.

“I have no reason to think he can’t carry the full load. He hasn’t had any flare-ups or setbacks.”

McCarthy said he “tried to give James (Starks) some work there at the end,” when Starks rushed five times for 11 yards late in the fourth quarter against Houston. Starks, who was active Sunday for the first time since sustaining a turf toe injury in the preseason opener, “needs live action,” McCarthy said.

PUP update: Since Smith is headed for IR and the Packers will have another roster spot open, they may opt to activate one of the three players on their Physically Unable to Perform (PUP) list.

OT Derek Sherrod , who broke his leg late last season, TE Andrew Quarless , who blew out his knee in 2011, and Frank Zombo , who badly injured his hamstring just before training camp, are the three Packers eligible to return after sitting out the first six weeks.

None have practiced, but McCarthy said Zombo and Quarless were “definitely ready,” while Sherrod was “further behind.” McCarthy said a decision would be made on them Wednesday.

Follow Packers reporter James Carlton on Twitter: @CBSPackers and @jimmycarlton88.