PHILADELPHIA — All that momentum, all those good feelings gone with one rim-rattling dunk that sent a juiced Wells Fargo Arena to its feet and sent the Nets home, stunned and defeated by the worst team in the league.

A day after their best offensive output of the season, the Nets were undone by the lowly 76ers, 103-98, in front of a boisterous crowd of 18,847.

With the 76ers up by 1 with 27 seconds left, T.J. McConnell collected a bad pass from Thaddeus Young at center court, fed Robert Covington, who dished to Nerlens Noel under the basket for the slam and the 99-96 lead. It is only the Sixers eighth win of the year against 43 defeats, and the loss draws the Nets (13-39) ever closer to the Eastern Conference basement.

“It’s on us,” Joe Johnson said. “The ball stuck. We forced a lot of shots . . . It’s on us as players to come out and be consistent, night in and night out. Ball movement would have hurt this team . . . We played right into their hands.”

T.J. McConnell, filling in for an injured Ish Smith, had 17 points. Jahlil Okafor had 22 points and 17 rebounds and Noel had 18 points and four steals, as the Nets gave up 23 points on 19 turnovers. Young led the Nets with 22 points and 10 rebounds — his 24th double-double of the year — but was scoreless in the first half. Brook Lopez added 17 points.

“It’s very frustrating because I know we’ve shown we can be better and we can do better,” Johnson said. “To just come out and have a start like the way we did is unacceptable.”

Especially since the Nets were so desperately hoping to build on the emotional high of their Friday night contest — an offensive onslaught against the Sacramento Kings where they had a season high in points scored (128) and made a season-best 18 threes. In that regard, the opening quarter of Saturday night’s game must’ve seemed like a cruel joke.

The Nets shot 29.4 percent in the first quarter, committing 11 turnovers and scoring only 12 points. Kendall Marshall’s jumper with four seconds left gave the Sixers a 24-12 lead. It was, Young said, simply the product of the Nets’ “boneheaded plays,” coupled with the Sixers’ extra effort.

The Nets managed to make the best out of the Sixers’ ineffectiveness in the second quarter, outscoring them 27-17 — cutting the deficit to two at the break and tied it four times in the third quarter before briefly taking a two-point lead.

“We have to validate what we did [Friday] night,” Tony Brown said after the game. “We had to do it again and be consistent with what we did [Friday] night . . . consistently get that energy and effort and focus and we’ll start to convert some of these games into wins.”

Notes & quotes: The Nets plan to begin interviewing for their open general manager position on Monday, according to a report published by ESPN, which cited sources close to the team. The Nets, who have been functioning under assistant GM Frank Zanin after Billy King was reassigned on January 10, are said to be considering former Raptors GM Bryan Colangelo and former Hawks GM Danny Ferry. Nuggets’ assistant GM Arturas Karnisovas and Rockets vice president Gersson Rosas are also in the mix, according to ESPN.