As Eli Manning took a step up and stood behind the lectern, an announcement was made that Odell Beckham Jr., would not be coming into the interview room but would instead speak in the locker room. Instantly, several members of the media bolted.

“Everybody leave,’’ Manning said under his breath, flashing a sly smile. “Go check on Odell.’’

Beckham is the face of the new Giants, but Eli is the face of the franchise and Sunday night, the franchise quarterback came up with an epic performance and found some of the pixie dust that he used to magically toss around in all those fourth-quarter comebacks.

With the odds stacked against him, with players falling by the wayside around him, with the lead gone and hopes dimmed, Manning found a way. His 54th pass of the night sailed high into the night and somehow found the hands of tight end Larry Donnell, who leaped over linebacker NaVorro Bowman to haul in a 12-yard touchdown pass with 21 seconds remaining to stun the 49ers and give the Giants a 30-27 comeback victory at MetLife Stadium.

“Big win for this team,’’ Manning said. “It was special.’’

As improbable as it sounded just three weeks ago, the Giants have gone from worst to first, as their three-game winning streak has catapulted them to the top of the NFC East — the only team above .500. The Giants (3-2) moved past the Cowboys (2-3 and riding a three-game losing streak without injured quarterback Tony Romo), Eagles (2-3) and Redskins (2-3). This sets up next Monday night’s Giants-Eagles clash at Lincoln Financial Field.

“That’s crazy,’’ guard Justin Pugh said about the Giants landing in first place. “I want to keep it that way.’’

The Giants led nearly the entire game, at times in complete control yet ahead only 13-6 at halftime. There were three lead changes in the final 4:29, with the 49ers taking a 27-23 lead with 1:45 remaining on Carlos Hyde’s 2-yard touchdown run, ending a jet-quick 80-yard drive all-too reminiscent of those Giants defensive fadeouts in the fourth quarter of their first two losses this season.

For more than a decade, Manning has been asked to save the Giants in these situations, but this one was more dire than most. When he took the field with 1:45 left on his own 18-yard line, surrounding him was a makeshift receiving corps, as hamstring injuries to Odell Beckham Jr. and Reuben Randle left Manning with Dwayne Harris, rookie Geremy Davis and recently signed Myles White as targets.

No matter. Manning completed his 27th career fourth-quarter comeback with an eight-play, 82-yard drive, needing a replay reversal to wipe away a potential game-deciding interception with 41 seconds left. The key plays were a 24-yard catch-and-run by Shane Vereen — “When Shane caught that ball the red seas parted,’’ coach Tom Coughlin said — and an 8-yard pass interference penalty on Kenneth Ackles, who grabbed Beckham after Beckham forced his way back into the game despite his hamstring issue.

“We were trying to win a game,’’ Coughlin said. “[Beckham] wanted to go. The medical people said let him go. I let him go.’’

The game-winner was a brilliant throw and catch, with Manning seeing Bowman in man coverage on Donnell and sailing a pass that Donnell had to use his entire 6-foot-6 frame to corral at the top of his jump.

“You’ve been there before and you know the situation,’’ said Beckham, who was so emotional he was brought to tears after the game. “In past situations we weren’t able to finish. It was just great to be able to finish in the fashion that we did. It was a lot of fun.’’

Manning was prolific and at his ice-vein best. He attempted a career high 54 passes and completed a franchise-record 41 for 441 yards. His only blemish was an interception near the end of the first half that cost the Giants a chip-shot field goal.

“It felt like we were in a good rhythm all day, the ball was coming out quick, we were seeing things well and guys were making some plays for us so it was fun,’’ Manning said. “ It was one of those days where you just felt good throwing it.’’

The Giants dominated the first half, yet led only 13-6. They could not come close to holding onto a 23-20 lead, as Colin Kaepernick made like Romo and Matt Ryan and shredded the Giants’ makeshift defense with a late fourth-quarter scoring drive.

The 49ers (1-4) came into the game on a three-game losing streak, outscored 107-28, and there were moments in the first half when the Giants appeared capable of adding to that misery. But it took a final-seconds rally to subdue the Niners, as the Giants vaulted themselves into first place.

“It says a lot,’’ Coughlin said, “about a bunch of guys who will hang in there.’’

Hero

Eli Manning carried the Giants on his back with career and franchise highs in completions (41) and attempts (54) while throwing for 441 yards and three TDs. The end-zone interception just before halftime was ugly, but the game-winning drive was a thing of beauty.

Zeroes

The pass coverage by 49ers defensive coordinator Eric Mangini’s unit was brutal. Giving up a big night to Odell Beckham Jr. was understandable, but six catches for 72 yards by Dwayne Harris? Four catches for 48 yards by Will Tye? Back to the drawing board, Mangenius.

Unsung hero

Shane Vereen showed why he is considered one of the best pass-catching backs in all of football. The former Patriots standout hauled in all eight passes thrown in his direction, totaling 86 yards and a TD in the process.

Key stat

9-of-14 Third-down conversions by the Giants, who continually frustrated the 49ers with vital conversions. None was bigger than Vereen’s 24-yard reception on third-and-10 on the final drive.

Quote of the night

“I had a couple of [fourth-quarter comebacks] in the Super Bowl … but this one is special, though.”

— Eli Manning on where Sunday night’s comeback ranked for him

— Bart Hubbuch