The Mavericks (2-3) led 71-67 going into the fourth quarter and took a seven-point lead at 94-87 with two minutes to play on Novak's 3-pointer.
"It was great," said Novak, 6 of 10 from 3-point range. "The biggest thing was we were able to hold them off and get the win. We were 1-3 coming into this game. We know we have to win some games in this preseason. It was a shooter's gym tonight."
Austin Daye had 16 points and five rebounds for Detroit (2-2). He was 3 of 6 on 3-pointers.
"I was looking at Novak's stats and he shot 10 himself," Daye said. "There were a lot of 3s to be had out there, and they had the better end of it."
Dominique Jones added 15 points for Dallas, and Tyson Chandler had seven rebounds.
"We only had 14 turnovers, which is the lowest we've had yet," Dallas coach Rick Carlisle said. "We've made a little progress yet."