Continued: A win, and early exit for Jackson

BALTIMORE -- Tarvaris Jackson has been told before that if he's going to scramble he needs to be prepared to hit the ground when defenders converge.

Odds are good he will now listen to that advice.

The quarterback was forced from the Vikings' 23-15 preseason victory over Baltimore on Saturday night at M&T Bank Stadium because of a bruised right knee suffered in the first quarter.

Jackson will undergo further tests today in the Twin Cities, but no one associated with the Vikings seemed worried as they prepared to leave Baltimore late Saturday. Jackson said his concern level was "very low" but also said, "You never know."

"He just banged his knee," coach Brad Childress said. "We're calling it a contusion right now. We were able to keep him in in the second half and settle that swelling down a little bit. I'm sure he'll be stiff and sore in the morning. We'll just see how he responds."

The Vikings had been hoping to see Jackson run the first-team offense for much of the first half.

But on the seventh play of Minnesota's second drive, Jackson took off running.

He gained 9 yards to the Baltimore 43 before being hit by Ravens linebacker Antwan Barnes and then safety Dawan Landry. Jackson said it was Landry's hit that did the damage.

Jackson was limping as he got up but remained in the game. "It felt funny," he said. "I thought it was going to go away. I stayed in for a couple to see how it was going to feel."

Running back Adrian Peterson gained 2 yards on the play after the hit; Jackson then completed a 12-yard pass to Sidney Rice.

Still limping, Jackson hobbled toward the Vikings bench before lying down on the field.

He spent the rest of the opening half on the sideline, first with an ice pack taped to the knee and then with a brace-like sleeve on the injury. Veteran backup Gus Frerotte replaced Jackson and remained in until Brooks Bollinger took over late in the second quarter.

Jackson said after the game that he was in no pain, and also that he believed it was simply a bruise.

"That's what I'm thinking, but I don't really know right now," he said. "I just got hit on it, so we're just taking it from there."

Jackson went 8-4 as a starter in 2007 but missed three games because of injuries. This included a strained groin, a concussion and a fractured index finger. The concussion happened when he took a hit at the end of a run against San Diego.

"I think he'll take it to heart now when you tell him, 'Hey, slide, run out of bounds, do those things,' " Frerotte said. "He's way more valuable to us on the field than he is in here."

Jackson knows he should slide but said, "It's just my instincts. I got to do what I've got to do to be healthy."

Jackson, coming off a strong performance during three series of action in the preseason opener against Seattle, picked up where he left off Saturday.

He completed four of six passes for 53 yards and also scrambled for 13 yards in leading the Vikings on an 11-play, 70-yard drive on their first possession. Jackson found a wide-open Martin Nance on a 23-yard scoring pass to cap the drive.

Frerotte completed four of nine passes for 69 yards and had a 5-yard touchdown pass to Robert Ferguson in the second quarter. "I sense that he's getting a pretty good feel of what we're doing systematically," Childress said.

The majority of the offensive starters played three series for the second consecutive week. Adrian Peterson got his first carry of the preseason in the first quarter and rushed for 30 yards on eight attempts. He also caught one pass for 22 yards.

The first-team defense played the entire first half (four series) as the Vikings took a 20-7 lead. The defense was improved against the pass -- Ravens quarterback Troy Smith was 3-for-5 for 25 yards -- but Baltimore rushed for 110 yards against a Minnesota run defense that was the best in the NFL last season.

This included a 42-yard dash by running back Ray Rice that helped to set up a Ravens touchdown on their opening drive.

Childress said he isn't pleased that the defense has given up touchdowns on the first two drives against it in as many games.

"I think the defense can start a bit faster," he said. "We'll adjust that."