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MINNEAPOLIS -- The San Diego Chargers escaped from a sloppy preseason game with some confidence in their defense.

Their kickers were in fine form, too.

Nick Novak's 45-yard field goal as time expired gave the Chargers a 12-10 victory Friday over Minnesota, after Vikings quarterback Christian Ponder struggled along with the rest of his starting offense.

Nate Kaeding made field goals of 50 and 54 yards for the Chargers, and Novak, who filled in last season when Kaeding was hurt, kicked two of his own.

The Chargers had a scare in the third quarter when first-round draft pick Melvin Ingram, the outside linebacker from South Carolina, limped off in pain after trainers looked at his left leg. But he was diagnosed with only a deep thigh bruise. Larry English had two of the team's five sacks.

"Larry has been unblockable for the last 10 days of camp," linebacker Takeo Spikes said. "We all know he can play, as long as he continues to stay healthy."

The most encouraging development for the Vikings was probably in pregame warm-ups, when running back Adrian Peterson took part in drills to continue to ramp up his rehabilitation. He's close to returning from reconstructive surgery on his left knee. The Vikings, though, lost promising rookie cornerback and punt returner Josh Robinson to a possible concussion in the second quarter.

Minnesota's offensive possessions in the first half? Punt, punt, missed field goal, fumble, interception, punt, punt and, finally, a 29-yard field goal by Blair Walsh.

"It was a little disappointing. It just shows that we have a lot to work on. We wish we would have performed like we did the first two weeks, but we know we have the capability to do so," Ponder said.

Sage Rosenfels threw a late touchdown pass to Matt Asiata, who lost one of three Vikings fumbles earlier in the second half. His was at the San Diego 2-yard line. Lex Hilliard and Derrick Coleman (at the San Diego 18) also coughed up the ball, and Ponder showed his inexperience while throwing an interception. He finished 9-for-16 for 115 yards.

"I think it's obvious we're growing as a defensive group, a lot more playmakers, and they're kind of just feeding off each other," Chargers coach Norv Turner said, adding: "It really is something to build on."

Further proving the irrelevancy of preseason results, the Chargers have won all three of their games despite a slew of injuries and a nonexistent running attack without starter Ryan Mathews, who is recovering from a broken collarbone and will miss another two to four weeks.

The Chargers are averaging barely 2 yards per carry in the preseason. Rookie Edwin Baker led the way with 13 yards on 35 rushes.

They rested quarterback Philip Rivers and tight end Antonio Gates, and the left side of the offensive line was out with injuries: center Nick Harwick (concussion), guard Tyronne Green (foot) and tackle Jared Gaither (back). The backups had a lot of trouble, too. All-Pro defensive end Jared Allen gave undrafted rookie Mike Harris, Gaither's replacement, all he could handle with two first-half sacks. Middle linebacker Jasper Brinkley had two sacks himself.

"If you're going against the backups or whatever, you should dominate," Allen said.

Wide receivers Vincent Brown (ankle) and Eddie Royal (groin) have been out, too, so Charlie Whitehurst didn't have much support. He finished 8-for-18 for 82 yards, but he stayed healthy, most importantly.

"As challenging as it was, I thought he handled it well," Turner said.

Whitehurst insisted getting hit a few times was welcomed.

"It felt pretty good. There are some pretty good players on the other side of the ball," he said.

After a solid performance in limited action over their first two exhibitions, Ponder and the Vikings' offense were anything but smooth. Playing into the third quarter, Ponder had spotty protection, taking five sacks, although he probably held the ball too long on at least two of them. Percy Harvin and Michael Jenkins each had catchable passes go in and out of their hands, too.

Ponder managed to throw a spot-on 40-yard completion to Harvin while Ingram tried to take him down by the shoulder, but many of his other passes were erratic. The worst one was in the second quarter when he pivoted to throw to Harvin on an out route toward the sideline without looking away first. Both Greg Gatson and DeAndre Presley were there, and Presley came down with the interception after they bobbled it together but kept it from touching the turf on their way down.

"He stared the route down, and I just did what my coaches have been teaching me," Presley said.

This was originally ruled an incompletion, as Hilliard's fumble was declared down by contact first. Both calls were overturned after the Chargers challenged on a busy night for the replacement officials crew led by referee Wayne Elliott. There were 20 penalties called, including 11 in the first half on the Chargers.

"That's not my concern. Everybody's got to play with the same refs," Allen said. "The league's going to do what the league needs to do; it'll work itself out."