The Bears are all alone in first place in the NFC North.
The Lions, who entered Week 15 in first place, are now third, falling behind the Bears and the Packers by losing Monday night to the Ravens 18-16 on Justin Tucker's final-minute, 61-yard field goal.
That's how close the race is.
The 8-6 Bears and the 7-6-1 Packers both won Sunday and have now moved ahead of the 7-7 Lions.
If the Bears win out, they're the NFC North champions and will be the No. 3 or No. 4 seed when the playoffs start, hosting a first-round game against one of the wild-card qualifiers.
The Bears are 3-point underdogs against the 8-6 Eagles Sunday night in Philadelphia. The Eagles also are locked in a close division race with the 7-7 Cowboys, but they would wrap up the NFC East with a win over the Bears, if the Cowboys lose their noon game at Washington.
The Bears conclude the regular season against the Packers at Soldier Field. The Packers host the 6-8 Steelers Sunday, and they hope to have injured quarterback Aaron Rodgers back for the Steelers, but he has not yet been cleared to return. Pittsburgh currently has only the slimmest of playoff hopes and could be eliminated by the time the 3:25 p.m. game begins.
The Lions host the 5-9 Giants this week and finish on the road against the 4-9-1 Vikings.
To win the NFC North over Detroit, the Bears must finish with a better record since the Lions own the tiebreaker, having swept their season series.
The defending Super Bowl champion Ravens, meanwhile, moved a step closer toward having a shot at defending their title. Tucker had a lot to do with that.
His franchise-record field goal with 38 seconds left lifted Baltimore over the Lions in a Monday night matchup with major playoff implications.
Ravens rookie safety Matt Elam sealed the victory with an interception -- Matthew Stafford's third of the night.
Stafford threw a 14-yard touchdown pass to Joseph Fauria with 2:21 left, putting Detroit ahead 16-15. But the Lions were unable to make a 2-point conversion and couldn't prevent Baltimore from setting up its sensational kicker for his sixth field goal of the game and 33rd in a row.
Tucker's kick went just inside the right upright and barely had enough distance, eight days after Denver's Matt Prater broke the NFL record with a 64-yard field goal.
"Didn't get all of it, got enough of it," Tucker said. "Just glad to get out of here with a victory at a time when the team needed one."
Tucker, who hasn't missed a field goal since he was 0-for-2 in Week 2 at Cleveland, has the NFL's longest streak since Matt Stover made 36 in a row for the Ravens from 2005-06, according to STATS.
Detroit has hurt its playoff chances by losing four of its last five. Stafford's 3 interceptions followed a troubling trend for the franchise.
He has 12 interceptions in his last five games. Not coincidently, the Lions have been able to overcome those miscues well enough to win only one game during the slump.
Ravens quarterback Joe Flacco didn't turn the ball over and made enough subtle moves in and around the pocket to get sacked only once. He has been sacked a career-high 42 times this season, but he stayed upright enough Monday night to move the ball into position for Tucker's big kick.
•Associated Press contributed to this report.