ATLANTA — The decision wasn’t made quickly, but the declarations were.
Mitch Trubisky had thrown another inexcusable interception in the third quarter Sunday — to a zone defender he didn’t see, with his team trailing by 13 points — when he jogged to the sideline at Mercedes-Benz Stadium.
Offensive coordinator Bill Lazor gave him the news.
‘‘Nick is up,’’ he said.
Backup Nick Foles got his promotion from coach Matt Nagy.
‘‘You’re in,’’ Nagy said. ‘‘Get warm.’’
And then Foles got red-hot, leading the undefeated Bears to another improbable comeback, this one a 30-26 victory against the hapless Falcons. Foles threw three touchdown passes in the last 6:20 of the game — totaling 20 points in 4 minutes, 27 seconds of football time — to rally the Bears from a 16-point deficit.
The Bears became the first team in NFL history to win two games in the same season in which they had trailed by 16 or more points entering the fourth quarter, according to the Elias Sports Bureau. And they’ve done it in three weeks.
Trubisky, of course, rallied the Bears to victory in the season opener against the Lions. Now, while Nagy wouldn’t say it outright, he has lost his starting job.
Nagy debated replacing Trubisky — who finished 13-for-22 for 127 yards, with a touchdown, an interception and a 71.8 passer rating — at halftime. The offense had no energy, he said, and little rhythm.
‘‘There was just something missing,’’ Nagy said.
The interception — to cornerback Blidi Wreh-Wilson, standing to the right of tight end Jimmy Graham — did Trubisky in. It felt like the right time, Nagy said, to make a move that seemed inevitable when the Bears traded a fourth-round draft pick for Foles during the offseason.
‘‘We discussed it, but we wanted to be able to go out and just kind of get a feel for how things would go,’’ Nagy said. ‘‘Then when that interception occurred, I think you just kind of felt like, ‘OK, we’ve got to make a move here.’ ’’
Foles put on his helmet and began talking to his linemen and receivers. Trubisky kept his helmet on but walked farther down the sideline, alone.
‘‘The only thing I can control is me playing better when I have those reps in the first half, and I didn’t do that,’’ Trubisky said. ‘‘So I gave [Nagy] the opportunity to pull me. He did.’’
One of the passes that will haunt Trubisky was his overthrow of a wide-open Anthony Miller on a third-and-two deep shot with a minute left in the first half. Had the pass been two yards shorter, Miller would have had a touchdown and Trubisky probably would have kept his job.
Amazingly, Foles ran the same play for the game-winner. The ghosts of blown leads past — a 20-point deficit erased by the Cowboys last week and, of course, the 28-3 Super Bowl rally by the Patriots — long ago had crept into the Falcons’ minds by the time Foles huddled his teammates during the two-minute warning. The Bears were down three and facing third-and-eight from the Falcons’ 28.
The Bears called two plays in the huddle, knowing the Falcons could blitz. Foles told Miller that if they did, he would loft the ball to the red ‘‘L’’ in ‘‘ATL’’ painted in the end zone.
When Foles sensed a zero blitz — one without safety help behind the cornerbacks — at the line of scrimmage, he checked the Bears into the right play and lofted the throw a split-second before getting crunched to the ground. Miller, lined up in the left slot, ran a post route past Wreh-Wilson, dove and caught the ball precisely on the ‘‘L.’’
Foles executed throughout his relief stint, even as the Falcons knew he would be throwing on almost every down. He completed 16 of 29 passes for 188 yards and finished with a 95.2 passer rating.
Amazingly, five of his six possessions — not counting the kneel-downs — ended in the end zone. Allen Robinson thought he had a touchdown, but the ball was wrestled away by cornerback Darqueze Dennard for an interception. Miller thought he caught a touchdown on a fourth-and-17 play, but the ball hit the ground. Both plays initially were ruled touchdowns but were overturned by replay.
Foles didn’t give his teammates a pep talk, but he stayed in their ears.
‘‘I don’t really worry about the score,’’ he said, ‘‘because you can’t score 16 points with one throw. You can only score six.’’
He did that two other times in the fourth quarter: a three-yard pass to Jimmy Graham, which cut the Falcons’ lead to 10, and a 37-yard pass to Robinson, who caught the ball at the 28 and ran through two arm tackles.
The Bears sealed the game with about a minute to go when safety Tashaun Gipson picked off Falcons quarterback Matt Ryan at the Bears’ 24.
Gipson was wowed by his own quarterback.
‘‘At the end of the day,’’ Gipson said, ‘‘what he did was nothing short of amazing.’’