The Giants and Bears slugged it out on an overcast and misty day that saw the Giants' defense explode for five sacks, two interceptions (both by Alec Ogletree, who also had a pick-6 in the bunch), and six forced fumbles, one of which was recovered by the Giants in the upset win.
Ogletree, who earlier in the week admitted to not having a season that met his high standards, set the tone on the second play from scrimmage with his third interception of the season and his second pick-6 of the year, that coming on a Chase Daniel pass intended for running back Tarik Cohen, which the linebacker returned eight yards to spot the Giants a 7-0 lead.
The Bears got a huge break on their first scoring drive of the game thanks to safety Curtis Riley failing to come up with an easy interception. Riley, who was all alone in the middle of the field, let the ball go right through his hands, which kept the Bears' scoring drive alive.
The Bears, who also managed to convert a 4th-and-1 on that drive, would cap the 10-play, 70-yard drive on a 2-yard touchdown reception by tight end Adam Shaheen to tie it up.
The Giants and quarterback Eli Manning struggled in the first half.
After going three-and-out on their first two possession of the first quarter, Manning, who was 7-of-17 for 73 yards and an interception for a 29.8 rating through 30 minutes of play, threw a bad interception on a pass intended for receiver Odell Beckham Jr.
Beckham was covered by Bears cornerback Kyle Fuller, who read the play perfectly and broke on the ball before Beckham did.
In the second quarter, the Bears took a 14-7 lead on tackle eligible Akiem Hicks' 1-yard touchdown run on a 4th-and-1. The Giants would make it 14-10 at the half on their final possession of the second quarter on a career-long 57-yard field goal by Rosas.
The Giants took back the lead in the third quarter with a pair of touchdown receptions. The first came on a gadget play that saw Beckham connect with Russell Shepard on a 49-yard touchdown after Beckham took the ball on an end-around play.
The second came on a well-designed shallow crossing route in which Manning hit Beckham in the back of the end zone on a 4th-and-1 to give the Giants a 10-point lead.
The Bears got a 36-yard field goal in the fourth quarter from Cody Parkey to make it 24-17 with 9:35 left in the game.
The Giants caught another break late in the game just before the two-minute warning when cornerback B.W. Webb forced a fumble on Bears receiver Taylor Gabriel that was recovered by Sean Chandler at the Bears' 13-yard line. The Giants then made it a two-score game.
But as has been the case with the Giants this year, the defense failed to finish the game, allowing the Bears to score 10 points in the final 1:49 of regulation.
Parkey hit a 21-yard field goal and then the Bears recovered the onside kick that led to a 1-yard pass from Tarik Cohen to receiver Anthony Miller to send the game into overtime.
But Rosas and the Giants' defense made certain to seal the deal for the Giants, who moved to 4-8 on the season and whose slim playoff hopes remain alive.
GAME NOTES: Giants running back Saquon Barkley finished with 125 rushing yards on 24 carries, passing Tuffy Leemans (830) for the most rushing yards by a rookie in franchise history. ... Beckham's touchdown pass was his second of the year and made him the second player since the 1970 AFL-NFL merger to have two passing touchdowns and five receiving touchdowns in the same season. The first was Rod Gardner in 2003. Beckham also became the first wide receiver with two touchdown passes in the same season since the Steelers' Antwaan Randle El in 2010. ... Giants linebacker Tae Davis was ruled out of the game in the first half after suffering an ankle injury. ... Receiver Sterling Shepard (ribs) and Landon Collins (shoulder) were also banged up but neither missed much time.