NEWARK, N.J. — The Celtics’ Big Three never had lost in New Jersey, which often feels more like the TD Garden than the Garden State when they visit.

Even they have to admit things are different now with the Nets, who won’t rule out having the Celtics returning for the playoffs.

Brook Lopez scored 20 points, Deron Williams added 16 and made the clinching 3-pointer, and the Nets extended their longest winning streak in three years to five games with an 88-79 victory Monday night.

Kris Humphries had 16 points and 15 rebounds, following his strong performance against Blake Griffin by turning in one against Kevin Garnett to help the Nets snap a nine-game home losing streak against the Celtics.

“We knew they’ve been playing well lately, playing with a lot more energy,” Garnett said. “(Williams), he’s come over here and gave them sort of like a winning mentality, seems to be working for them. Kris is playing really well for them, Brook is playing really well. They have players that are playing really well, just they’re trying to put it together it seems like.”

It’s working. New Jersey has won five straight for the first time since Dec. 28-Jan. 5 in the 2007-08 season, the Big Three’s first. And though a huge long shot with a 5½-game deficit to overcome in the last month, the Nets aren’t out of the postseason race yet.

“I think we’re playing good right now, we’re gelling pretty well, having such a short time together. We’re having fun,” Williams said. “These games are important right now, not only because we have a chance to make the playoffs, but for the future and going forward next year.”

Ray Allen scored 19 points and Garnett had 18 for the Celtics, who couldn’t overcome horrible shooting nights from Paul Pierce and Rajon Rondo, and fell back into a tie with Chicago for the best record in the Eastern Conference.

A night after allowing a franchise low in points in the shot- clock era in an 87-56 victory against Milwaukee, the Celtics wasted a good defensive effort with a bad offensive one. Pierce was 2 of 10 for seven points; Rondo shot 1 of 10 and scored two.

Rondo, who went down after a hard pick in the first half and briefly went to the locker room in the third quarter, missed his first seven shots before making a jumper with 3:10 left in the third quarter. He said he tweaked his ankle but was fine.

“Obviously we didn’t shoot well. I didn’t shoot well,” Rondo said. “We’ve got to get better looks at the basket. I know we had a lot of wide-open shots, some shots we made, a lot of shots we missed tonight that we usually make.”

The Nets beat the Celtics in New Jersey for the first time since April 16, 2006, and agreed this victory had extra meaning, since the previous four in their winning streak came against losing teams.