At this point it appears the Packers will have only three healthy tailbacks for Saturday night's preseason opener in Pittsburgh, but the ones who can play are prepared to play as long as they're asked to.

"If it's the whole game, I'll play it," rookie second-round draft pick Brandon Jackson said. "If I have to play it on my knuckles, I'll play it. Don't matter."

Jackson will start the game as the No. 1 running back, and Head Coach Mike McCarthy said after Thursday night's practice that Jackson would play at least the first half. Behind him will be Noah Herron and combo back Corey White.

All three scored touchdowns during a red zone team drill Thursday night. Jackson scored on a short plunge up the middle, Herron ran one in off the left side, and White made a catch along the end zone sideline when quarterback Brett Favre scrambled to his right.

Already down to four tailbacks this week because of knee injuries to Vernand Morency and P.J. Pope, the Packers also lost rookie DeShawn Wynn this week to a quad strain. Wynn missed both practices on Thursday and McCarthy said it appears unlikely he'll be ready to play on Saturday.

The Packers were almost dealing with yet another injury Thursday morning, when Herron was slow to get up after some contact with defensive back Tyrone Culver on a pass route. Herron took a mild shot to the throat and struggled to get air for a few minutes, but he was fine and returned a couple of snaps later.

The "veteran" of the running back group as a third-year pro, Herron doesn't think it will be a problem to carry a hefty load for this first preseason game. In fact, he's hoping it works to his advantage.

"The more you can play I think the better early on, getting back in that rhythm really quick," Herron said. "Football is a game of ups and downs, but the more you play, the more reps you can get, the more you can be on that 'up'."

With only three healthy tailbacks, that could mean double-digit carries for each one before the game is over. That would be a tremendous opportunity for White, who initially was playing more fullback but has switched almost exclusively to tailback because of the injury situation.

A non-drafted rookie out of Alabama-Birmingham, White is on some return and coverage units as well, so he could end up having a very busy evening.

"I'm going to be on special teams too, so I'm trying to condition myself in practice to go out there, suck it up and stick it out when I can," he said. "I don't think there's ever too many reps. I look at it as more of a chance to show what you can do."

Corners questionable

Starting cornerbacks Al Harris (back) and Charles Woodson (hamstring) sat out Thursday evening's full-pads workout, and McCarthy said it was questionable whether they would play on Saturday.

"We'd like to have (all) the No. 1's go out and play," McCarthy said. "We're looking about probably 12 to 15 plays. It's not really (Harris and Woodson) individually, it's playing with everybody else. But we'll make that call tomorrow."

Patrick Dendy and Jarrett Bush were the corners with the No. 1 defense Thursday night and would likely start on Saturday if neither Harris nor Woodson can play.

{sportsad300}Quarterback switch

In the battle for the No. 3 quarterback job, Ingle Martin is scheduled to play the entire fourth quarter on Saturday, according to McCarthy, with Paul Thompson sitting out. Then in the second preseason game on Saturday, Aug. 18, at Lambeau Field against Seattle, they would swap and Thompson would play the fourth quarter with Martin taking a rest.

"I've always felt, particularly with the quarterback, every series it's so hard to get in a rhythm and things like that," McCarthy said. "It's beneficial to give that third slot a quarter, hopefully get something established and get rolling. I've found the results to be better that way."

Preparing for Pittsburgh

During both practices Thursday, the offense and defense took snaps against scout teams mimicking some of the Pittsburgh Steelers' schemes.

One defender who made a couple of very quick reads in the morning work was starting safety Nick Collins. On one sideline throw, Collins jumped the route and probably should have had an interception with a clear return path for a touchdown, but he failed to hold onto the ball. On another play, Collins made a quick break on a short throw over the middle to Carlton Brewster and broke up the pass.

In the evening practice, several other defenders made standout plays during team work. Safety Tyrone Culver intercepted an overthrown fade pass along the sideline, and cornerback Frank Walker made an interception near the goal line, though he tried to make an ill-advised lateral to Tramon Williams that was fumbled in the end zone, with Williams needing to fall on it and take a likely safety.

Also, linebacker Brady Poppinga burst into the backfield and put a big hit on Jackson for what would have been a significant loss, and Dendy made a nice pass break-up as Thompson tried to scramble and connect with Calvin Russell.

Going back home

McCarthy will be coaching an NFL game in his hometown of Pittsburgh for the first time on Saturday.

In his previous NFL coaching stints in Kansas City, New Orleans and San Francisco, anytime McCarthy's team played the Steelers, Pittsburgh was the road team.

McCarthy said it will still primarily be a business trip, but he plans to visit his family for a couple of hours on Friday night to have dinner.

Still working on versatility

Backup offensive lineman Tony Palmer was taking a lot of snaps as the No. 2 center earlier in the week, but Thursday he was back at guard with the second line. Tyson Walter was the No. 2 center.

It's not unusual for the coaches to shift linemen around, particularly the backups, to evaluate who can be the most versatile as a reserve.

Injury, participation update

Receiver Greg Jennings (hip flexor) and offensive tackle Chad Clifton (knees) both returned to practice on Thursday and are expected to play. Offensive tackle Orrin Thompson (back) also returned to practice.

Fullback Brandon Miree and offensive lineman Tony Moll both missed Thursday's workouts with stingers and would be evaluated again on Friday as to their availability to play. McCarthy didn't sound overly optimistic about either player.