Brook Lopez goes off for 20 points, headlining five Nets in double figures on the night. Kris Humphries contributes 16 points and 15 rebounds for the Nets, who have now won five straight games.
Ray Allen scores 19 for the Celtics, Kevin Garnett 18 and Glen Davis 16.
At 47-18, the C's are now tied with the Bulls for first place in the Eastern Conference.
They return home to face the Indiana Pacers on Wednesday night.
Fourth quarter, 35.6 seconds, Nets 86-79: Deron Williams knocks down a 3. That's the shot of the night.
The C's just can't win on back-to-backs, can they?
Fourth quarter, 40.7 seconds, Nets 83-79: The Celtics are in real trouble now. Brook Lopez connects on a deadly hook shot, Glen Davis misses on the other end, and the Nets have the ball back.
Do or die for the C's now. Get a stop or go home crying.
Fourth quarter, 1:46, Nets 81-79: The Celtics get their big stop, as Kevin Garnett smothers Deron Williams and the Nets' last-second attempt to swing the ball falters. They've got the ball back and a chance to tie it.
Glen Davis has been red hot in this fourth quarter, hitting every shot in sight. Can he knock down one more to bring the C's all the way back?
Fourth quarter, 2:21, Nets 81-79: Right when Paul Pierce is on the verge of taking the lead with a wide-open look for 3, Kevin Garnett gets whistled for a three-second violation. The Nets catch a big break here and get the ball back.
The Celtics could really use a stop now.
Fourth quarter, 3:40, Nets 81-77: The C's are still making their push, but Rajon Rondo throws a big wrench in their momentum by fouling Anthony Morrow in the act of shooting a corner 3.
Morrow gets to the line and hits two of the three shots.
Rondo now has five fouls.
The C's can't make any mistakes from here on out. They've got to play virtually perfect basketball to steal this one.
Fourth quarter, 6:14, Nets 77-71: The Celtics keep on charging back. KG and Jeff Green score on back-to-back possessions, and the lead is six.
Avery Johnson has called for a full timeout. He's the master of rallying his troops to play tough D. Let's see if the Nets can get the job done now.
Fourth quarter, 7:39, Nets 74-67: The Celtics are slowly sneaking back into the ballgame, as a Jeff Green free throw caps off a 5-0 run. The C's are back within seven.
They're doing it with Rajon Rondo off the floor, surprisingly. Carlos Arroyo is seing some serious fourth-quarter minutes.
Has anyone ever earned Doc Rivers' trust faster than Arroyo?
Fourth quarter, 9:32, Nets 74-62: Travis Outlaw for three. That's the ninth trey of the ballgame for the Nets as a team.
This one's starting to slip away, folks. The Nets are on fire, and the C's just can't catch up.
Fourth quarter, 9:56, Nets 71-62: Even when his Nets climb out to a double-digit lead, Avery Johnson isn't missing an opportunity to bicker with the refs.
The Nets get an illegal defense tech; Paul Pierce makes a free throw.
End of third quarter, Nets 67-61: With a pair of deep 3s, one from Anthony Morrow and one from Sundiata Gaines, the Nets pull ahead of the Celtics in the final minute of quarter No. 3.
The C's have gotten 17 points from Ray Allen and 16 from Kevin Garnett, but the supporting cast hasn't given them enough. Brook Lopez, Kris Humphries and the Nets' shooters have taken this game over.
Boston has 12 minutes to turn this thing around.
Third quarter, 3:10, 56-56: Rajon Rondo makes the Nets pay for disrespecting him, connecting on a mid-range jump shot. The C's have tied the ballgame again.
The C's are staying in the ballgame right now despite a questionable effort, which is more than you'd expect from this team on day two of a back-to-back.
We'll see if they've got enough in the tank to close this one out. You never know with these C's.
Third quarter, 5:25, Celtics 50-49: Rajon Rondo is back, and that's good news for the Celtics. But it doesn't change the fact that Brook Lopez and Kris Humphries are both terrorizing them down low.
Lopez now has 14 points, Humphries has 12, and the Nets nearly have themselves a lead. Where did this come from?
The C's need to show some toughness down low. KG and Big Baby aren't putting up a fight right now.
Third quarter, 8:08, Celtics 46-41: Deron Williams looks revitalized by Rajon Rondo coming out. He's attacking now more than ever.
That means two things — one, D-Will is getting to the line at will, and two, he's thus putting the C's in bad foul trouble. Paul Pierce now has four, and he's headed to the bench for a while.
The C's will have to keep the offense afloat without him. Here's where Ray Allen may step up.
Third quarter, 10:01, Celtics 44-39: The good news for the Celtics is that Paul Pierce is smashing faces and taking names, most recently Kris Humphries on that monster slam. The bad news is that Rajon Rondo's ankle doesn't look good.
Rondo comes off the floor and heads to the locker room. He's having trouble putting weight on that leg. That's troublesome.
Carlos Arroyo checks in for Rondo. The C's might need big minutes out of Arroyo again tonight.
Halftime, Celtics 38-36: It's not quite as absurd as Sunday against the Bucks, but the Celtics have put forth another fairly solid defensive effort in New Jersey. Not bad for the second night of a back-to-back.
The C's lead the Nets 38-36 at halftime, getting a 10-point burst from Ray Allen to keep them ahead going into the locker room. Deron Williams is flirting with a triple-double for New Jersey — he's got nine points, five rebounds and four assists already.
The Celtics are outshooting the Nets considerably, 41.9 percent to 32.5. It's been a pretty ugly game on both sides offensively.
Second quarter, 2:52, Nets 30-29: Now it's the Celtics' turn to fall apart offensively. They've now gone a full three and a half minutes without scoring, while the Nets have gone on a quick 8-0 run.
Doc Rivers is getting his reserves get plenty of minutes tonight, on the tail end of a back-to-back. Glen Davis and Jeff Green have each seen 11 minutes off the bench.
The C's need Rajon Rondo and Ray Allen to get out there an make an impact before halftime. They've gotten nothing out of their two starting guards.
Second quarter, 5:49, Celtics 29-22: The Celtics have a 12-2 advantage in bench scoring already. Glen Davis leads the way for the C's reserves with six points.
Having Baby back as a reliable bench scorer is a key for this team. He may have missed a week and a half with a knee injury, but it's taken him no time at all to find his rhythm again.
Second quarter, 8:21, Celtics 25-21: Brook Lopez just beat Glen Davis to an offensive rebound and put it back with ease. Man, that's a big size advantage down low.
This new-look second unit, integrating Big Baby with all the new guys, is looking decent at times. But rebounding has been an issue so far. Everyone's underperforming on the glass — except Troy Murphy, who's already pulled down three boards off the bebnch.
Murphy isn't scoring much yet (besides his 12 points in garbage time Sunday), but if he can crash the boards a little bit, that alone would make a huge impact.
Second quarter, 9:19, Celtics 23-16: The Nets' offense has looked extremely predictable so far. Every play is run within the Deron Williams/Kris Humphries two-man game. The other three guys mostly just stand there watching.
D-Will is a tremendous weapon
End of first quarter, Celtics 21-14: Yet another tremendous defensive first quarter for the Celtics. The C's hold the Nets scoreless for the final 6:28 of the first quarter, going on a 14-0 run to close it out.
The Nets got instant offense early from Kris Humphries, but they've got dead silent. They've missed their last 10 shots.
Humphries has seven of the Nets' 14 points; Kevin Garnett and Nenad Krstic have six each for Boston.
First quarter, 2:06, Celtics 17-14: The Celtics have struck back in a hurry, going on an 8-0 run of their own. Nenad Krstic pours in the last four points himself.
Yet another big first quarter for Krstic. Who needs Shaquille O'Neal?
First quarter, 5:42, Nets 14-9: The Nets are now on a 7-1 run. So much for KG controlling this game on both ends.
Deron Williams has been really solid so far, but the real hero of the first quarter is Kris Humphries, who has dazzled for the Nets with seven of their first 14 points.
Time for KG to step up and nip that in the bud, hmm?
First quarter, 7:12, 9-9: We're seeing an alarming trend, as the Nets have already stretched the Celtics to the buzzer of the shot clock a few times in this first quarter. The C's need to get into their offense faster and be more efficient.
All too often, these drawn-out possessions end in off-balance jumpers being chucked in the final second. The C's have the weapons to make those jumpers, but they also have the smarts to be better than that. This isn't Celtic basketball.
First quarter, 10:28, Celtics 6-5: Scary moment for the Celtics early, as Rajon Rondo collides with Kris Humphries on a very hard pick in transition.
The Celtics call a timeout, just to make sure Rondo's OK. Looks like he's a little shaken up, but he's going to fight his way through it.
First quarter, 11:23, Celtics 4-0: The Celtics eventually come away with the opening tip, and they come out firing. Kevin Garnett hoists up two quick jump shots on the Celtics' first two possessions, making them both. That's an awfully quick 4-0 lead.
The Celtics are a really dangerous team when KG spreads the floor. Watch for the Big Ticket to open things up for Nenad Krstic and Rajon Rondo to drive and score.
7 p.m.: If you bleed green, then there are two intriguing matchups tonight on the NBA's nine-game slate — one's the Celtics taking on the Nets, and the other is Kendrick Perkins making his debut for the Oklahoma City Thunder against the Wizards.
Watch 'em both, if you're hardcore like that. Picture in picture, or get two TV sets side by side. Do what you gotta do.
Tonight's a big night for Celtics past and present alike.
6 p.m.: The Celtics are again suited up in their St. Patrick's Day-themed green and gold uniforms for Monday night's road contest against the Nets.
Stay tuned for this one. You don't want to miss the C's getting their first look at Deron Williams in the Nets' home whites. The Atlantic Division is about to get a lot more interesting, and we're going to witness it live.
8 a.m.: The heat is on in the Eastern Conference playoff race (if you'll excuse the pun). The Celtics won a big one on Sunday afternoon, 87-56 over the visiting Milwaukee Bucks, but all that did was keep them even for the weekend with the Bulls (who beat the Jazz on Saturday night) and the Bulls (who likewise beat the Grizzlies).
The C's remain just a half game up on Chicago, and three ahead of Miami. Every game counts, and everyone's feeling the pressure — even the new guys who just jumped into this environment weeks or even days ago.
"Definitely," said Carlos Arroyo, who was playing for the Heat last month. "This is a team that's hungry to win it again, and it's a team that understands what it takes to win it. We have a bunch of veterans that can win, and I'm truly grateful to be a part of this."
This playoff race is going to go down to the wire, and every Celtic will eventually be caught up in it, from one to 15.
The Celtics have just 18 games left to go, and the next one comes against the New Jersey Nets at the Prudential Center on Monday night. After Sunday's victory over the Bucks gave them six wins in their last eight, the C's will now take on a team that's even hotter. Avery Johnson's Nets have won four straight.
Glen Davis returned Sunday from a knee injury and played well; his rhythm is starting to come back. The next guy to bounce back should be Delonte West, who's on the way back from a sprained ankle this week.
Every game is vital for the Celtics, who continue to eye that No. 1 seed. Tipoff against the Nets is at 7 p.m. Monday.