As the Vikings head into Sunday's game against the Packers, here are four questions we're trying to answer.

1 Sunday's game seems like a lopsided matchup in so many ways. Given the Vikings' injury woes, what is the biggest area of concern?

Friday's big news: Cornerback Antoine Winfield is doubtful to play again because of lingering stiffness in his neck. Winfield returned to practice on a limited basis this week but still is not ready for game action. Safety Jamarca Sanford (concussion) might not be either and is also tagged as doubtful.

So the Vikings secondary is missing two key cogs about to face a Packers offense that features a deep and talented receiving corps. With Aaron Rodgers as their quarterback. Oh boy.

Given the way Rodgers spreads the ball around and the frequency with which Green Bay gives him four targets to choose from, labeling the Vikings secondary as vulnerable is generous.

Tyrell Johnson likely will start in place of Sanford with rookie safety Mistral Raymond in line to be activated for the first time this season. Second-year corner Marcus Sherels should expect to see considerable time in dime packages.

Circle the more impressive starting unit: Packers receivers Greg Jennings, Jordy Nelson and James Jones plus tight end Jermichael Finley; or Vikings defensive backs Cedric Griffin, Chris Cook, Husain Abdullah and Johnson.

2Is quarterback Christian Ponder wired to remain confident during prolonged stretches of struggle?

For the past month, Ponder has become a Twin Cities favorite, the bottle of Excedrin fans have been reaching for to treat their pounding headaches. And now that Ponder has his chance to start? Well, quarterbacks coach Craig Johnson sat down with the rookie earlier in the week with a reminder.

"Everywhere I've ever been, everybody loves the backup quarterback," Johnson told Ponder. "And guess what? You're not the backup anymore."

Yep, Johnson expects the critic line to start building around 3:30 p.m. Sunday at Mall of America Field. After all, he and Ponder are realistic enough to acknowledge that errors are forthcoming. But throughout the organization, people say there's confidence that Ponder has the perspective and maturity to accept his mistakes without agonizing over them.

Said Johnson: "The bottom line is learn from it. Try not to make the same mistake twice. Move on and when you have that storm or that slump -- and it is coming -- guess what? We'll get through it. We'll go down, we'll get the pictures, you'll get a drink of water."

3 Speaking of quickly moving, are there concerns about Ponder relying too much on his mobility?

Offensive coordinator Bill Musgrave said Ponder has a sixth sense for sensing pressure. But Musgrave also hopes the rookie understands that what would have been a 12-yard scramble in college might now be a 1-yard gain -- with a big-time wallop added to the end.

"If you looked at the film at Florida State, he was a fearless runner. Fearless," Musgrave said.

"Which is an attribute. But at this level, with the guys playing defense, you have to be smart. Otherwise, you won't stay upright. You won't stay in the league very long, healthwise."

4And who will be snapping Ponder the ball?

With center John Sullivan doubtful to play while still recovering from a concussion, Joe Berger should get the call. Berger, remember, didn't join the Vikings until Week 2 after the team waived Jon Cooper. Berger started 14 games in Miami last season but was cut by the Dolphins in early September. The Vikings quickly reacted, believing Berger's experience and size (6-5, 305 pounds) could be valuable. Now, they will test that theory on the big stage.

Said coach Leslie Frazier: "As long as he doesn't feel that the pressure of the world is on my shoulders and I have to do [more] than my job, he'll be fine. ... He's a smart guy, a tough guy and he knows our offense."