The Los Angeles Rams came out on top in a defensive duel with the San Francisco 49ers on Thursday, seizing three of their four field goals in the final quarter and triumphing 12-6 to boost their NFL playoff hopes.

Rookie kicker Joshua Karty emerged as the star at a sodden Levi's Stadium, where driving rain hindered both offenses in the first half.

Karty's 23-yard field goal to cap a 17-play drive tied it at 6-6 with 13:38 left in the fourth quarter.

He drilled a 27-yarder on the Rams' next drive for a 9-6 lead.

San Francisco were in field goal range on their ensuing possession, but Brock Purdy's long pass into the end zone was intercepted by Darious Williams.

The Rams ate up the clock with a final drive capped by Karty's fourth field goal with 18 seconds remaining.

"This team can win a variety of ways," said Rams coach Sean McVay, whose team was coming off a 44-42 victory over Buffalo in the highest-scoring game of the season.

"I thought the defense came up big, time in and time out," added McVay, who also praised the poise of quarterback Matthew Stafford in the tough conditions.

Stafford connected on 16 of 27 pass attempts for 160 yards and the Rams improved to 8-6, moving a half-game behind NFC West division leaders Seattle.

Counterpart Brock Purdy completed 14 passes for 142 yards and neither team had a touchdown.

San Francisco were on the board first with a 53-yard field goal from Jake Moody early in the first quarter.

They took a 6-3 lead on a 47-yard field goal by Moody early in the third.

But the game ended with a sack of Purdy, the defeat a further blow to the already slim playoff hopes of the 49ers, who fell in last season's Super Bowl to the Kansas City Chiefs.

Niners wide receiver Deebo Samuel, who had complained this week on social media that he was not getting the ball enough, had three catches with a conspicuous drop of a third-down pass in the third quarter.

© Agence France-Presse