Tucker's field goal as time expired secured the Ravens an eighth straight win which took them to the top of the AFC.
MVP contender Lamar Jackson threw for one touchdown and rushed for another in wet and windy conditions in Baltimore.
The 49ers remain top of the NFC following their second loss of the season and could meet the Ravens again in the Super Bowl in Tampa in February.
The Ravens replaced New England at the top of the AFC standings as the Patriots were beaten 28-22 by the Houston Texans.
Deshaun Watson threw for 234 yards and three touchdowns and caught another in a statement performance from the 8-4 Texans.
Tom Brady threw for 326 yards, three touchdowns and an interception as the Patriots suffered a second defeat of the season.
Dalton found Tyler Boyd for a 17-yard touchdown in the first quarter and he led another two scoring drives before half-time at the Paul Brown Stadium.
The Kansas City Chiefs took control of the AFC West with a 40-9 win over divisional rivals the Oakland Raiders.
Patrick Mahomes threw one touchdown and ran in another inside the first half with a Juan Thornhill interception giving the Chiefs a 21-0 half-time lead.
LeSean McCoy and Darwin Thompson also found the endzone in the second half as the Chiefs improved to 8-4.
The Pittsburgh Steelers sparred off against the Cleveland Browns after their game earlier in the season was marred by an altercation between Myles Garrett and Mason Rudolph, with Garrett hitting Rudolph on the head with his helmet.
The game was a more civil affair, the Steelers coming from 10 points down to win 20-13 and strengthen their wild card hopes.
Kicker Jason Sanders caught a touchdown pass as the Miami Dolphins saw off the Philadelphia Eagles 37-31 and Tye Smith returned a blocked field goal as the Tennessee Titans defeated the Indianapolis Colts 31-17.
The Green Bay Packers beat the New York Giants 31-13, the Washington Redskins defeated the Carolina Panthers 29-21 and Peyton Barber had two rushing touchdowns as the Tampa Bay Buccaneers saw off the Jacksonville Jaguars 28-11.
Jared Goff threw for 424 yards and two touchdowns as the Los Angeles Rams thrashed the Arizona Cardinals 34-7 and the Denver Broncos edged out the Los Angeles Chargers 23-20.