"It's huge any time you play a good team, but particularly when you play them on the road," Carlesimo said. "Honestly, this is a big-time win. It's a great, great win."
Russell Westbrook had 26 points and 10 assists for Oklahoma City, which lost for only the third time at home this season.
The Thunder clamped down after trailing by 16 at halftime, rallying to pull within 71-68 when Westbrook finished off a 12-3 burst with a jumper from the left elbow with 3:47 left in the third quarter. Lopez powered his way in for a two-handed slam to stem the tide for Brooklyn, but Oklahoma City kept coming.
Durant and Kevin Martin connected on consecutive 3-pointers to finally even it up at 85 with 7:11 to play, only for Johnson to answer with a runner at the other end to put the Nets right back ahead and start the clinching run.
Brooklyn shot exactly 50 percent, becoming just the second team to hit at least half of its shots against Oklahoma City.
"Offense is not what lost us the game. It's not because we didn't make enough shots or we didn't have enough assists," Durant said. "We just didn't play any defense."
Carlesimo spoke as though he held no grudge against the Thunder, who replaced him — then on an interim basis — with Scott Brooks, who has overseen the team's rise into a championship contender.
Back when Carlesimo was in charge, Durant was starting his second year in the NBA and Westbrook was a rookie who had yet to break into the starting lineup. Now, they're both established All-Stars.
"It's a team I feel closer to than a lot of other teams. Hopefully, we helped KD and Nick (Collison) a little bit and Russell a tiny bit that first year, but I think it's safe to say they've gone on and overcome whatever coaching they got from me," Carlesimo said, drawing laughs.
At the start, it looked like Carlesimo's new squad would run away with it against the Thunder, who started the day with the league's best record.
Johnson and Lopez combined to go 9 for 9 from the field to propel the Nets to a quick 27-11 lead, and the lead grew to as much as 23 twice — including at 55-32 after Johnson drilled a 3-pointer off a touch pass from Wallace.
Notes: Carlesimo's only win with the Thunder — after the SuperSonics had relocated from Seattle — came at home on Nov. 2, 2008, against Minnesota. ... The Thunder's largest previous deficit of the season was 16 in a loss at home against Memphis. ... Oklahoma City got a delay of game warning for failing to get onto the court in time for tip-off, as part of the NBA's emphasis on allowing teams 90 seconds between the end of introductions and the tip-off. ... Nets reserve Jerry Stackhouse sat out with a sore right hamstring.