John Kasay kicked a 26-yard field goal to win it.
“I know it will be scrutinized all week long,” Smith said. “I want everybody to understand I take full responsibility.”
New Orleans (7-3) took control of the N.F.C. South race, snapping Atlanta’s three-game winning streak. But the game will be long remembered for Smith’s gutsy and ill-fated call, especially if the loss comes back to cost the Falcons a return to the playoffs.
Atlanta (5-4) rallied from a 10-point deficit in the fourth quarter, tying it on Matt Bryant’s 27-yard field goal on the final play of regulation.
In overtime, Atlanta appeared to pick up a first down on a pass to Mike Cox, but he was ruled just short after referee Terry McAuley looked at the replay. Then, stunningly, Smith decided to go for it on fourth down from his own 29.
Michael Turner was stuffed on a rushing attempt. That decided the game.
“We were going to be aggressive in all that we did,” Smith said. “Unfortunately, it did not work out.”
After each offense went three-and-out on its first possession of overtime, Atlanta faced third-and-1 from the 29. Matt Ryan flipped a pass to Cox, the backup fullback, who was met short of the 30 but stretched his right arm, appearing to place the ball across the line. It was initially ruled a first down, but the replay showed that Cox bobbled the ball as he was going down along the sideline, and the spot was moved back.
The Falcons initially sent on the punting team, then called a timeout. Smith decided to go for it, figuring his team could pick up the foot or so needed to keep the drive going. That turned out to be a big mistake.
Ryan handed off to the bruising Turner, but he never had a chance. He was swarmed by a group of defenders and actually lost a couple of feet, and the jubilant Saints took over. Four plays later, Kasay won it with his fourth field goal of the game.
“I just saw a guy in my face as soon as I got the ball,” Turner said. “I would like to have it back. I would love to be in that situation again.”
Sean Payton of the Saints coached the game on crutches in his return to the sideline after a collision with one of his players left him with a broken left leg and severe knee injuries nearly a month ago.
“I just felt like this was an important game,” Payton said. “That presence is important. I talked to the doctors this morning.”
Drew Brees completed 30 of 43 passes for 322 yards and 2 touchdowns for New Orleans. Marques Colston had eight catches for 113 yards.
The Saints were glad to have their coach among them, not sending down calls from the booth.
“It was great having him, just his presence,” Brees said. “He couldn’t wait to get back down there. He has his hands in everything.”
Ryan threw 52 passes, completing 29 for 351 yards and 2 touchdowns. Harry Douglas became his favorite receiver after the rookie Julio Jones left the game, sidelined again by an ailing hamstring. Douglas finished with eight receptions for 133 yards.
Turner rushed for 96 yards, but could not get the one yard that mattered most.
“We’ve just got to get a couple inches. Make that play and move on,” center Todd McClure said. “I like the fact our coach has faith in us to make the play.”
Brees was impressed by Smith’s courage, if nothing else.
“It takes some steel and you-know-what to make that call,” he said. “This one play is the game.”
In regulation, Atlanta was down to its last chance, facing fourth-and-3 at the New Orleans 45 with about four and a half minutes remaining. Ryan kept the drive going by hitting Roddy White on a 6-yard completion, then struck quickly with two more passes to make a game of it. A 19-yarder to White was followed by a 20-yard touchdown pass to Tony Gonzalez with 4 minutes 13 seconds to go, bringing the Falcons to 23-20.
With only one timeout remaining, the Falcons tried an onside kick. It did not work.
The Saints moved into position to give Kasay a 45-yard try. He drilled the kick right down the middle, but Jimmy Graham was called for holding and New Orleans decided to back up the Falcons with a punt.
After Eric Weems made a fair catch at the Atlanta 5, the Falcons put together a clutch drive that forced overtime. Ryan connected three times with Douglas on completions totaling 66 yards, and Atlanta had plenty of time to take three shots at the end zone for a winning touchdown.
After three incompletions by Ryan, Bryant kicked his third field goal.