Playing near the home of suspended coach Sean Payton, Brees threw for 446 yards and three touchdowns. He led a drive to Garrett Hartley's 20-yard winning field goal in overtime, and the Saints damaged Dallas' playoff hopes with a 34-31 victory Sunday.
The Saints all but secured the win when a fumble by Marques Colston rolled forward about 20 yards to the Dallas 2. Jimmy Graham recovered.
The Saints (7-8), who started 0-4 after getting stunned by Payton's yearlong ban in the team's bounty scandal, saw their playoff hopes end with Minnesota's victory against Houston. The Cowboys (8-7) had a three-game winning streak snapped and lost control of their playoff fate.
Dallas lost despite rallying for two touchdowns in the final 3:35 of regulation. Tony Romo, who threw for 416 yards and four scores, hit Miles Austin for the tying touchdown with 15 seconds left in regulation.
The Cowboys' last three games have been decided on the final play. Dallas' best hope for the playoffs rested with the New York Giants' game at Baltimore on Sunday. A Giants loss would give the Cowboys, who play at Washington in next week's finale, a chance to win the NFC East. They also could make the playoffs as a wild card.
After New Orleans forced a punt on the first possession of overtime, Brees moved the Saints to the Cowboys 33. He completed a pass to Colston, who took a couple of steps before Morris Claiborne stripped the ball, sending it rolling toward the end zone. The completion was held up on review after Graham won a scrum with Dallas' Eric Frampton for the ball, and Hartley made the winning kick.
The Cowboys pulled within a touchdown on a 16-yard pass from Romo to Dwayne Harris and got the ball back with 1:29 remaining. Romo led the Cowboys 64 yards in seven plays, capped by the tying toss to Austin, who caught the ball on his knees in the end zone.
Romo also had a pair of 58-yard scoring passes to Dez Bryant, who had a career-high 224 yards receiving.
Dallas tight end Jason Witten had two catches in overtime, breaking Tony Gonzalez's NFL season record of 102 catches for a tight end set in 2004. Witten has 103.
The Saints, coming off a 41-0 blowout of Tampa Bay, took the lead in the third quarter after a 54-yard punt pinned Dallas at its 3. On the first play, Curtis Lofton stripped DeMarco Murray and Lofton recovered at the 5. Brees found Pierre Thomas open at the goal line for a 24-17 lead.
The Cowboys then put the Saints at their 2 on a 63-yard punt, but Brees responded with a touchdown drive keyed by a 60-yard completion to Colston, who had 153 yards receiving. Colston broke a tackle by Gerald Sensabaugh before Sterling Moore ran him down at the Dallas 3.
The Saints turned a 14-7 deficit late in the first half into a 17-14 halftime lead in the final 1:11.
Brees led a 90-yard scoring drive that included interim coach Joe Vitt changing his mind and going on fourth-and-1 from the Dallas 23. A completion to Colston was overturned on replay, but Cowboys linebacker Anthony Spencer lined up offside to give the Saints a first down anyway. Brees threw a 6-yard scoring pass to Lance Moore three plays later.
The Cowboys used their timeouts while New Orleans had the ball, hoping to score before halftime. The Saints scored instead on Garrett Hartley's 37-yard field goal on the final play of the half after Dallas went three-and-out. A 44-yard screen pass to Darren Sproles put the Saints in position.
Romo's pair of 58-yard scores to Bryant turned a 7-0 deficit into a 14-7 lead. The first was a deep pass that Saints cornerback Patrick Robinson never saw, and he couldn't find Bryant after the catch. On the second, Robinson missed a tackle on a short pass and Bryant stiff-armed Isa Abdul-Quddus around the 40 and coasted to the end zone.
Bryant tied a franchise record with a touchdown catch in his seventh consecutive game, and he matched his career high of 145 yards receiving before halftime.
Brees easily drove the Saints to a touchdown on their first possession and was on his way to a 14-0 lead when the Cowboys stuffed the Saints twice with a yard to go for a first down from the 18. Three plays after Hartley was wide left on a 36-yard field goal, Romo found Bryant for the first long score.