Fran Tarkenton is no doubt the greatest Vikings quarterback of all time, and he watched Teddy Bridgewater on Sunday, when the second-year pro posted a 50.9 passer rating in the 31-14 victory over San Diego, less than half the 120.6 he had against Detroit last week.

Bridgewater completed only 13 of 24 passes for 121 yards and threw an interception in the end zone, and he did not throw a touchdown. He was outplayed by San Diego veteran Philip Rivers, who had an 81.2 rating after he completed 21 of 34 passes for 246 yards and a touchdown going against an excellent Vikings pass rush, although Rivers also had a costly interception, one returned 91 yards for a score by Chad Greenway.

Tarkenton doesn't get to many Vikings games, but he was at this one to honor his former center Mick Tingelhoff's entrance into the Pro Football Hall of Fame.

Tarkenton said this about Bridgewater: "I think he is progressing nicely. [Vikings offensive coordinator] Norv Turner is a great coach, he's a [Jerry Burns]-like coach, and that's a good thing.

"Bridgewater is smart, getting better. Is he going to be perfect? Nobody is perfect. He's going to make some plays, but everybody is going to make bad throws. What I'd say about Teddy Bridgewater is the moment is not too big for him, the arena is not too big for him. He's relaxed, he's confident. The No. 1 thing a quarterback has to have is confidence, and then relaxation."

What does Bridgewater have to do to improve?

"He just has to keep working at it, keep understanding, listen to Norv Turner," said Tarkenton, who also was here for a book signing at the Mall of America. "He needs to get all the knowledge he can, get smarter every day, and work at it, which he's doing and will do. If he continues to do that, he'll make significant progress. Every week, every month, every year, you'll see a better Teddy Bridgewater."

When it came to his opinion of running back Adrian Peterson, Tarkenton ran out of words of praise.

"Peterson is great. He's one of the greatest running backs ever to live," Tarkenton said. "I've said the only guy I would compare to [Hall of Fame running back] Jimmy Brown is Adrian Peterson."

The Vikings played a great defensive game for the second week in a row, and Tarkenton took notice.

"We're playing great defense. I know Mike Zimmer is a head coach but he's a great defensive coach, and we're doing what we have to do," he said. "We have to play great defense. We have some playmakers on defense and they're keeping us in games."

Tarkenton said this team should compete for a playoff spot after missing for the past two years. And he believes the Vikings can even win the NFC North over the Packers, who have won the division four years in a row.

"They have a great chance for the playoffs this year, make that step, if not win the division, then a wild card," he said. "I think we're competitive with Green Bay or anybody. Detroit or Chicago is not going to do anything. I think it's going to be a Green Bay/Minnesota fight as it has been many times.

"I think they can beat the Packers. Aaron Rodgers is a mature, great, wonderful quarterback, probably the greatest quarterback in football today. He is a load. He has great experience. Remember that Aaron Rodgers sat on the bench for two years behind Brett Favre. The Packers? I don't think they scare you on defense. They don't scare you with the offensive and defensive line. I think we have a better roster than Green Bay, but they have Aaron Rodgers right now."

Griffen produces

One of the smartest things Viking General Manager Rick Spielman did in recent years was sign Everson Griffen to a multiyear contract last year.

The defensive end made life miserable for Rivers, continuing his strong play from this season and last.

"[Rivers is] getting the ball off quick anyways, he's getting the ball off 1-2-3," Griffen said. "He don't like getting hit. So … when he held the ball we had to go back there and hit him, and that's the time to get sacks."

Asked how much the Vikings defense has improved from Zimmer's first season, Griffen said: "The defense improved immensely. The second year in the defense and everyone is playing faster, playing smarter and we're running into the ball and making plays.

"We just do what we do. Our whole purpose is to rush the passer and have our back end cover us and that's what they did. Good things happen when you play team football."

Griffen did get tagged with a roughing-the-passer penalty, but it ended up not hurting the Vikings. "I wasn't trying to hit him, I was trying to hold him up, it just happens sometimes," he said.

Greenway gets TD

Greenway, a Vikings first-round pick in 2006, has seen his playing time decrease this season, but the linebacker made perhaps the biggest play of the game when he returned his interception nearly the length of the field.

"It was pretty sweet, obviously the ball popped up," he said. "Great play by the D-line and obviously great blocking by the team, that made it easy for me to get in there."

It was his 10th career interception and second career score, his first coming in 2007 against the New York Giants. This one was notable for how many teammates accompanied him down the field.

"There was a convoy, blockers everywhere," Green­way said. "By the time I hit the sideline, I looked around and there were probably 9-10 guys there. I could jog in. They made it look easy."

As for how the defense played, he said: "The guys played really well. Obviously our front dominated their line. They had a lot of injuries on their side, but I think our defensive front really won the game for us."

Jottings

• Dan Fouts, the former Chargers star quarterback who broadcast the game for CBS, predicted great things for the Vikings because they are fortunate to have two stars in Peterson and Bridgewater.

• The Chargers had 369 yards of offense to the Vikings' 284, but the game wasn't nearly that close, at least not as it advanced in the second half. San Diego got a garbage touchdown when Zimmer played many reserves late in the game.

• San Diego running back Melvin Gordon, the Heisman Trophy finalist at Wisconsin last year, found out Sunday how much difference there is between NFL and Big Ten defenses. Against the Gophers last fall, he ran 29 times for 151 yards. Sunday, he ran 14 times for 51 yards, much of it coming against reserves. Said Gordon's former high school teammate Trae Waynes, who played well on defense for the Vikings when he filled in at cornerback for the injured Xavier Rhodes: "I felt like we game-planned him pretty well. He's a great player and we played him pretty well."

Sid Hartman can be heard weekdays on 830-AM at 7:40 and 8:40 a.m. and on Sundays at 9:30 a.m. shartman@startribune.com