A “Let’s Go Giants!” chant rose up out of MetLife Stadium’s north end zone in Sunday’s third quarter. Then just as quickly, the building shook with disgust.

Daniel Jones had fumbled away the Giants’ comeback try, sandwiched by Denver linebackers Josey Jewell and Alexander Johnson on a scramble.

They knew to rip at the ball. They did. And that, plus a turnover on downs on a last gasp Giants’ drive, sealed the franchise’s fifth straight opening day loss, a 27-13 dud defeat to Denver.

The worst sign for Joe Judge’s Giants, though, was that their defense failed to show up.

Broncos QB Teddy Bridgewater converted three fourth downs, all on scoring drives. The biggest was a killer 4th-and-1 TD pass to tight end Albert Okwuegbunam from the 4-yard line with 6:48 remaining in the third for a 17-7 Denver lead.

Bridgewater stiff-armed safety Xavier McKinney to make the throw, and linebacker Blake Martinez missed his tackle on the tight end.

Jones and Sterling Shepard mounted a response with two connections for 35 yards on the ensuing drive, only for Jones to give away possession and the game on Denver’s 13-yard line.

Broncos offensive coordinator Pat Shurmur, Judge’s predecessor as Giants head coach, then iced the game with a Brandon McManus field goal and a 70-yard Melvin Gordon touchdown run.

Jones added a 4-yard Giants rushing TD for posterity as time expired. He finished 22-of-37 for 267 yards and a passing TD, plus 27 yards on the ground and that late score.

Saquon Barkley played for the first time since tearing his ACL in Week 2 of last season, but he was a shell of himself, clearly tentative on his right knee.

The Giants had seven rushes for eight yards in the first half, and Barkley had 10 carries for 26 yards for the game.

As a team, the Giants also disappointingly lost their composure on Sunday. Corner Darnay Holmes committed a dumb personal foul in the first half, and Danny Shelton and Azeez Ojulari each had personal fouls on Bridgewater in the second.

The Broncos’ offense was 7-of-12 on third downs at one point before finishing 7-of-15, in addition to Denver’s 100% fourth down conversion rate.

The Philadelphia Eagles (1-0) are now alone in first place in the NFC East with the Giants (0-1), Dallas Cowboys (0-1) and Washington Football Team (0-1) all losing.

Judge’s Giants must turn around quickly for a Thursday Night Football test down at Washington, who likely will start QB Taylor Heineke after Ryan Fitzpatrick left Sunday’s loss to the Chargers with a hip injury.

The Giants trailed 10-7 at halftime after a demoralizing end to the second quarter.

With the home team up 7-3 midway through the second quarter, safety Logan Ryan made an incredible strip and fumble recovery on Okweugbunam at the Giants’ 4-yard line to bail out Holmes from his penalty deep in Giants territory.

But Jones’ offense went 3-and-out while pinned deep, and the Broncos promptly went 57 yards in seven plays for a 2-yard TD pass from Bridgewater to Tim Patrick to take the lead with eight seconds left.

Jones had given the Giants a 7-3 lead with 8:56 left in the first half on a 37-yard TD pass to Shepard. Shepard (seven catches, 113 yards, 1 TD) had beaten rookie corner Pat Surtain II across the field and then danced and turned up the sideline to the end zone.

Running back Devontae Booker, who had made a one-handed catch for 6 yards earlier, had a terrific chip block on Broncos edge Malik Reed to buy Jones time.

But that drive would account for the Giants’ only points until their final possession in garbage time.

New addition Kenny Golladay came on late with four catches for 64 yards, including one contested grab and another diving stab. He also drew a pass interference call to get the Giants deep into the red zone late in the fourth.

But he was also Jones’ 4th down target when Kyle Fuller batted the pass away in the end zone for a turnover on downs. Gordon’s TD followed shortly after.

Rookie first-round pick Kadarius Toney played three snaps and had two touches for minus-2 yards. His first touch was a horrendous call by offensive coordinator Jason Garrett, a jet sweep from left to right directly into Von Miller (two sacks) for a 6-yard loss.

That loss undid a 42-yard Jones pass to Darius Slayton that had brought the Giants to the Broncos’ 30.

It was a step back. A fitting start to a discouraging day that ended with an empty stadium save for the cheering orange Broncos jerseys, which grinds co-owner John Mara worst of all.