BALTIMORE — Neither rain, wind nor the San Francisco 49ers’ top-ranked defense could prevent Lamar Jackson from guiding the Baltimore Ravens to their franchise-record eighth straight win.

Jackson weathered miserable conditions to run for 101 yards and Justin Tucker kicked a tiebreaking 49-yard field goal as time expired to give the Ravens a 20-17 victory Sunday in a possible Super Bowl preview.

The combination of driving rain, a stiff wind and San Francisco’s rugged defense was difficult for Jackson to handle. He completed only 14 of 23 passes for 105 yards and lost a fumble.

But the double-threat quarterback was solid when it counted. Not only did he fuel the NFL’s top-ranked rushing attack, but he directed a clutch drive that lasted nearly 6½ minutes before Tucker ended it with a kick that tore through the raindrops and between the uprights.

Baltimore (10-2) improved to 16-3 with Jackson as a starter and 12-0 when he rushes for at least 70 yards. In addition, Jackson became the first quarterback in NFL history to have four 100-yard rushing games in a season.

Raheem Mostert ran for a career-high 146 yards and a touchdown for the 49ers (10-2), now tied with New Orleans for the best record in the NFC.

Jimmy Garoppolo went 15 of 21 for 165 yards for San Francisco.

Jackson lost a fumble for the first time this season when Marcell Harris yanked the wet ball from his grasp 0 in the third quarter.

The 49ers subsequently got a game-tying 32-yard field goal from Robbie Gould.

In the fourth quarter, both teams failed to convert a fourth-down try before the Ravens faced a fourth-and-1 from their 44 with 4:39 left. Jackson ran off right guard for 3 yards to extend the drive.

A 12-yard pass to tight end Mark Andrews gave Baltimore a first down at the San Francisco 39, and the Ravens soon summoned Tucker to end it.

Mostert ran for 89 yards before halftime — surpassing his previous career high in a game — but Gould missed a 51-yard field-goal attempt as time expired in the second quarter.