The Hornets trailed 92-85, then Marco Belinelli hit a 3 and Emeka Okafor put back Belinelli's missed reverse layup.
Dallas' Tyson Chandler, who had 16 points and 13 rebounds in his return from a sprained ankle, missed two free throws with 17 seconds to go leaving the game up for grabs.
Jason Kidd fouled Jack on a 3-point attempt, setting up Jack's decisive free throws with 8.4 seconds left. Jack finished with 21 points.
Dallas still had one more chance to win it, but for the second time in New Orleans this season, Dirk Nowitzki was unable to convert.
In San Antonio, the hosts bounced back from a humbling loss by beating Detroit.
Tony Parker scored 23 points and Tim Duncan -who matched a career low with two points in a blowout loss to the Los Angeles Lakers on Sunday - finished with 15 points and 12 rebounds in 31 minutes.
Richard Hamilton led the Pistons with 20 points off the bench.
The Spurs hit their first 14 shots and finished with a season-high 40 points in the first quarter to take a 14-point lead. San Antonio scored just 37 points in the first half in Sunday's loss.
In Philadelphia, Kevin Durant had 34 points and 16 rebounds to lead Oklahoma City over Philadelphia.
Russell Westbrook added 27 points and 12 assists for the Thunder.
Durant erased a five-point deficit with a minute left in regulation, hitting a runner and a 3-pointer that sent the game into overtime. The Sixers scored only two baskets in the extra 5 minutes.
Jrue Holiday and Lou Williams each scored 22 points for the Sixers.
Durant, the NBA's leading scorer, was 13 of 26 from the field and all 16 boards were defensive ones.
In Charlotte, Chicago pulled away in the fourth quarter to beat Charlotte, a victory dimmed by Carlos Boozer's leg injury.
Derrick Rose and Kyle Korver scored 20 points, with Korver scoring 12 in the final period for the Bulls, who won for the 11th time in 13 games and expanded their hold on second place in the Eastern Conference to 2½ games over slumping Miami.
Boozer limped off late in the game after his left leg bent awkwardly on a flagrant foul by Kwame Brown and didn't return.
Gerald Henderson had 20 points and eight assists for the Bobcats, who suffered their sixth straight loss.
In Boston, Los Angeles withstood a late Boston surge for its fourth straight win despite a mediocre performance by Blake Griffin.
Mo Williams scored 28 points in his highest haul since being traded by Cleveland. DeAndre Jordan had 21 points for the Clippers.
The Celtics were led by Ray Allen with 23 points, but lost for the first time in six games.
In Memphis, Carmelo Anthony made a 19-footer with less than a second left to allow New York to resist a late Memphis rally.
The winning shot by Anthony, who finished with 31 points, came after Zach Randolph's three-point play with 14 seconds remaining pulled Memphis even.
Memphis had one more chance after Anthony's basket, but an alley-oop attempt to Darrell Arthur was broken up at the basket, giving the Knicks their third straight win and strengthening their hold on the sixth playoff spot in the Eastern Conference.
Amare Stoudemire added 26 points for the Knicks.
Tony Allen led Memphis with 22 points, missing only one of his eight shots.
In Sacramento, Jameer Nelson scored 12 of his 26 points in the fourth quarter to lift Orlando over Sacramento.
Dwight Howard returned from a one-game suspension to have 16 points and 15 rebounds but fouled out late for the Magic, who overcome an eight-point deficit and open a five-game road trip with a much-needed victory.
DeMarcus Cousins had 29 points for the Kings, who upset the Magic earlier this season but collapsed late in this one.
In Toronto, Al Jefferson scored 34 points, including a game-winning layup at the buzzer, as Utah rallied from a 14-point deficit to beat Toronto for the 12th straight time.
C.J. Miles and Devin Harris each scored 23 points for Utah.
DeMar DeRozan scored 17 points as Toronto lost for the fifth time in six games.
In Newark, New Jersey, Brook Lopez had 26 points and 10 rebounds, and made two clinching free throws with 3.3 seconds left as New Jersey beat Golden State for its first three-game winning streak in two years.
Anthony Morrow added 22 points for the Nets.
David Lee had 17 points and 10 rebounds for the Warriors.
In Minneapolis, Kevin Love recorded his 52nd double-double in a row to surpass Moses Malone for the longest such streak since the ABA and NBA merged in 1976, and Minnesota downed free-falling Indiana.
Love overcame a bruised left knee to put up 16 points and 21 rebounds in just 27 minutes to help the Timberwolves win for just the 16th time this season. Love reached the double-double with just under seven minutes to play in the first half.
Tyler Hansbrough scored 21 points for the Pacers, who shot a season-low 29 percent to lose their fifth straight game.
In Milwaukee, Brandon Jennings and Earl Boykins each scored 18 points to lead Milwaukee over Cleveland.
Boykins had all of his points in the first half, then Jennings scored 14 in the third quarter as Milwaukee enjoyed its second blowout in two days, thanks to 55.1 percent shooting.
Samardo Samuels scored 11 of his 15 points in the first quarter for Cleveland, which lost for the fifth time in six games.
