Detroit, MI -- (Sports Network) - Frank Gore rushed for 159 yards and scored a touchdown, then left the game with a concussion, as the San Francisco 49ers held on to beat Detroit, 19-13, at Ford Field.

Gore, who was held to a season-low 41 yards on 19 carries in a win against the Vikings last Sunday, carried 22 times and also hauled in two passes for 14 yards. He left early in the fourth quarter and was being evaluated for symptoms of a concussion. There was no immediate word on his condition.

Alex Smith finished 14-of-20 for 136 yards passing for the 49ers (4-5), who recorded their second consecutive victory. Arnaz Battle led the receiving corps with six catches for 55 yards.

Joe Nedney converted all four of his field goal attempts to account for 12 of San Francisco's 19 points.

Joe Kitna completed 19-of-30 passes for 202 yards, throwing one touchdown and an interception for the Lions (2-7), who turned the ball over four times in the contest.

"It's hard to judge whether you're flat or not," said Kitna. "I think what this team needs to realize is and mature to the point of understanding how important every possession is. When you're fighting and scratching you give yourself no room for error in terms of record--every single possession is important . We can't take plays off and downs off. So we'll look at the tape and you have to give credit to San Fransisco, they came in here and played as hard as I've seen a team play in a long time."

Detroit was coming off a huge 30-17 win over Atlanta last weekend but the sixth-ranked passing offense in the NFL managed just one offensive score in the game.

Kevin Jones tallied 44 yards on the ground on 13 carries and added nine catches for 71 yards in the loss.

San Francisco jumped out early, taking a 7-0 lead on the opening series. On 3rd-and-16 Gore took a handoff on the draw and rumbled 61 yards to the end zone. The score capped a six-play, 79-yard series and exposed a Lions' defense that came in ranked 20th against the run.

Later in the half, the 49ers took advantage of a Jones fumble at the Detroit 32. Mark Roman jumped on the loose ball and five plays later Nedney split the uprights from 28 yards out to give San Francisco a 10-0 lead with 1:36 left to play in the first quarter.

Nedney also made good on a 23 yard attempt to finish a drive that bridged the first and second quarters. The field goal capped an 11-play, 73-yard march that was briefly interrupted when the Lions challenged a first-down ruling. After review, the call stood but the 49ers offense couldn't move the chains again, coming up one yard short on 3rd-and-8 from the Detroit 12.

The Lions cut the deficit to 13-3 on Jason Hanson's 25-yard field goal with 18 ticks remaining before the break.

Detroit's misfortunes continued in the third quarter, as Kitna was sacked by Shawntae Spencer at his own 22 and lost the ball. San Francisco recovered and the Lions issued their second challenge of the game, arguing that Kitna's arm was moving forward on the play and the call should be overturned as an incomplete pass. The officials, however, didn't agree and the ruling was upheld. That fumble recovery led to another 23-yard field goal from Nedney to put San Francisco up by a 16-3 margin.

On the Lions' next possession, Kitna's pass to Roy Williams was caught, but Williams was stripped of the ball and it was recovered by Manny Lawson. The Niners then moved the other way, but Smith fumbled on a short burst at mid-field and Detroit took over once again.

The ensuing 10-play drive came to a close with Dan Campbell pulling down an eight-yard TD pass from Kitna that closed the gap to 16-10 with 3:40 remaining in the third.

San Francisco, though, reclaimed a nine point advantage when Nedney connected on his fourth field goal of the afternoon, a 47-yard boot, with 12:29 remaining.

Hanson's 33-yarder with 7:57 remaining made it 19-13 and finished off a nine play drive that started at the Detroit 35.

Then, with 4:22 remaining, Kitna threw a deep pass down the middle to Williams, who was bumped by Keith Lewis. The safety was flagged for defensive pass interference, good for a 26 yard penalty. Two plays later, Kitna threw a short pass to Jones, who caught and then appeared to fumble the ball but was ruled down by contact. San Francisco head coach Mike Nolan was quick to throw the red flag to contest the decision, but the call stood and the 49ers were charged with their final timeout.

Four plays later, Kitna's pass on 4th-and-13 was intercepted by Lewis and the 49ers moved the chains one final time to seal the victory.

"We get two in a row, a road victory. Get some confidence going," said Smith afterward. "We're young, we're still learning a lot. This is big for our confidence. We came out hot, but didn't put a lot of points on the board. Get down in the red zone and didn't do as well and had to kick a lot of field goals. Obviously we kept them around, they came back and made it a game."

Game Notes

Gore set a franchise record with 148 yards rushing in the first half...Detroit has not scored on their opening drive this season...The 49ers lead the all- time series, 32-26-1, and have won 10 of the past 11 games.