The Nets, who entered the game 5-52 and 2-27 on the road, took a 29-27 lead on Keyon Dooling's jumper at the end of the first quarter and never trailed again.
The Celtics cut an 18-point fourth-quarter deficit to six on Ray Allen's 3-pointer with 2:05 left, but Kris Humphries' layup and two foul shots by Lopez ended the rally.
The Celtics didn't hit a 3-pointer until Nate Robinson's shot late in the third quarter and finished 3 of 19 from behind the arc while the Nets hit six 3-pointers in 13 attempts.
The Nets scored 25 points off 18 Celtics turnovers. Boston, coming off a 108-88 loss to the Cleveland Cavaliers at home Thursday, shot 63 percent in the first quarter and had a 12-2 lead, but the Nets, led by Harris' 11 points, charged back to take a 29-27 lead at the end of the quarter.
Lopez continued to hurt the Celtics inside in the second quarter and the Boston bench struggled. Lopez's tip-in with four minutes left in the first half gave the Nets a 46-36 lead.
New Jersey led 74-64 after three quarters and then started to pull away in the fourth. Chris Douglas-Roberts' dunk upped the lead to 12 with 7:44 left and Dooling's 3-pointer gave Jersey an 18-point advantage with five minutes left.
The Celtics hope to get Pierce back for Tuesday's game against Detroit.