— The New York Giants began the postseason just as they ended the regular season, with a solid performance — and a victory — under win-or-else circumstances.

They used three touchdown passes by quarterback Eli Manning, a significant contribution by their running game and dominant defense to beat the Atlanta Falcons, 24-2, in a first-round NFC playoff game Sunday at MetLife Stadium.

“I think today we played outstanding defense,” Giants Coach Tom Coughlin said, “and that set the tone for everything else that happened in the game. . . . If we can continue to play defense like that, we can make ourselves heard in this tournament.”

The fourth-seeded Giants advanced to a conference semifinal next Sunday in Green Bay against the top-seeded Packers. It will be a rematch of a Dec. 4 game here in which the Giants pushed the then-undefeated Packers to the limit before quarterback Aaron Rodgers directed Green Bay to a last-second field goal to prevail, 38-35.

There was no such drama in this one. Manning gave the fifth-seeded Falcons an early safety but rebounded to throw two touchdown passes to wide receiver Hakeem Nicks and another to wideout Mario Manningham.

The Giants moved the ball effectively on the ground with running backs Brandon Jacobs and Ahmad Bradshaw, a rarity for them this season, and the defense stuffed Atlanta quarterback Matt Ryan on two critical fourth-down quarterback sneaks.

“They won the line of scrimmage,” Falcons Coach Mike Smith said.

The defeat dropped Ryan’s career playoff record to 0-3 and left Falcons tight end Tony Gonzalez still without a postseason triumph in his 15 NFL seasons. The Giants were coming off consecutive wins over the New York Jets and the Dallas Cowboys at the end of the regular season to capture the NFC East title. 9-7 regular season record

The Falcons had to play without cornerback Brent Grimes, who had a knee injury. That seemed to be a promising combination for Manning and his two 1,000-yard receivers, Nicks and Victor Cruz.

But both teams struggled on offense in the early going. The Falcons finally crafted a promising drive but reserve running back Jason Snelling was stopped a yard shy of a first down on a third-and-two carry. Smith gambled and left his offense on the field on fourth down at the New York 24-yard line, but Ryan got nowhere on a quarterback sneak on the opening play of the second quarter.

“The fourth-down stops were huge,” Giants defensive end Justin Tuck said.

The Giants took over but promptly surrendered a safety when Manning was called for an intentional grounding penalty in the end zone.

The Giants finally began moving the next time they had the ball. They ranked last in the league in rushing offense during the regular season, while Manning’s passing carried the offense. But Manning got things going with a 14-yard scramble on a third-and-two play and Jacobs provided a 34-yard run later in the drive. The Giants had 172 rushing yards in the game, including 92 by Jacobs and 63 by Bradshaw.

“The running game got going pretty good,” Nicks said. “Everything was clicking.”

Jacobs picked up two tough yards and a first down on a fourth-and-inches gamble from the Atlanta 6-yard line. That led to Manning’s four-yard touchdown pass after Nicks got a step on cornerback Dominique Franks, Grimes’s replacement in the Falcons’ starting lineup.

The Giants quickly gave themselves an opportunity for another touchdown on their first possession of the second half, picking up a first down at the Atlanta 5-yard line on a 30-yard dash by Bradshaw. But that chance yielded only a 22-yard field goal by place kicker Lawrence Tynes.

The Falcons attempted to respond immediately and Ryan’s third-and-15 completion to wide receiver Roddy White left them a yard shy of a first down, with the ball at the New York 21-yard line. Smith again left his offense on the field, and Ryan again failed to gain ground on a quarterback sneak.

Said Giants defensive end Osi Umenyiora: “When it’s fourth and one, fourth and inches, and you go for it and a team stuffs you, I mean, how do you respond from that? It’s hard to recover from that. It’s basically that team telling you they’re stronger than you.”

The Giants needed only three plays to increase their lead to 17-2. Nicks caught a third-and-three pass from Manning around the 32-yard line, sped through the middle of a group of would-be Falcons tacklers and cut left toward the sideline on his way to a 72-yard touchdown.

“If we can get the run game going like we did in the second half, that opens up a lot of windows for the passing game,” said Manning, who completed 23 of 32 passes for 277 yards and didn’t throw an interception.

Manning made an on-target throw, dropping a pass between two Atlanta defenders, for a 27-yard touchdown to Manningham that put the game out of reach with just less than 10 minutes to play.