MEMPHIS, Tenn. -- With a 19-point lead to start the second half, the Memphis Grizzlies seemed to be on the verge of rolling to victory Thursday night at FedExForum.

But the good defense that had helped build that advantage went away. So did the share-the-ball offense.

"We were too passive, too content with the lead," said point guard Mike Conley, who finished with 22 points and four assists in what ultimately was a hard-fought 96-91 victory over the Dallas Mavericks. "We let them back in the game."

The Mavs (1-5) almost beat the Grizzlies for the second time in a little more than 24 hours after winning by nine points Wednesday night at the American Airlines Center in Dallas.

Training by 19 points at halftime Thursday night, the Mavericks finally caught and overtook the Grizzlies at the 3:56 mark in the fourth quarter when guard J.J. Barea (nine points, four assists) was fouled on a 3-point attempt and knocked down all three free throws for an 86-84 lead.

The advantage didn't last long. Conley hit a 3-pointer just before the shot clock expired to put Memphis up 87-86 with 3:31 left. Conley then made a driving layup to extend the lead to three points, and Dallas never was able to tie the game after that, but did pull to within a point at 92-91 when Harrison Barnes (22 points, 11 rebounds) hit a trey with 15 seconds to go.

"I'm built for fourth quarters," Conley said, "to take shots when somebody else might not."

Conley, who missed two free throws with 35 seconds remaining, hit four in the last 21 seconds as the Grizzlies sealed the win, thus not wasting a 25-point, 13-rebound performance from center Marc Gasol.

"I was frustrated," Conley said of the misses at the line. "I told everybody I wanted to get back to the free-throw line so don't pass to anybody else. I wanted to get fouled."

Memphis (4-1) led 54-35 at the break, but Dallas cut that down to 76-68 going into the fourth quarter. Guard Wesley Matthews (18 points) spurred the Mavericks' 33-point third quarter by hitting 4 of 6 3-point attempts for 12 points.

"The second quarter was a killer," Dallas coach Rick Carlisle said. "I loved the fight for three of the four quarters."

Matthews took little solace from the Mavs' second-half comeback.

"We shouldn't have been in that position in the first place," he said. "We put ourselves there."

Grizzlies coach David Fizdale said the Mavs' speed and youth got them off balance in the second half.

"They really got after us and forced us into some tough shots," Fizdale said. "I thought we messed with the game tonight, too, for whatever reason -- messing around with the ball and stuff and being careless with the basketball."

The Mavericks shot 34 percent from the floor and went 10 of 34 from 3-point range. Memphis shot 41.1 percent from the field while also going 10 of 34 from long distance.

Memphis got 19 points off the bench from guard Tyreke Evans. Starting forward Jarell Martin had nine points, nine rebounds and five blocks.

Dirk Nowitzki chipped in 14 points and seven rebounds for the Mavericks.

The Grizzlies committed 18 turnovers, the same number they had in the loss in Dallas a night earlier. That gave the Mavs a chance to take them down again.

"They got us playing one-on-one and we got a little happy with that," Gasol said. "We got enough stops, especially at the end, to stop the bleeding."

NOTES: Mavericks coach Rick Carlisle, G Wesley Matthews and F Dirk Nowitzki all picked up first-half technical fouls. ... Dallas G Devin Harris had missed three games following the death of a family member in a car accident, though he played Wednesday night in Dallas against the Grizzlies. He did not travel with the team to Memphis for the Thursday game. ... This was the Grizzlies' first set of 16 back-to-back games of the season. Memphis was 11-6 last season when playing on the second night of consecutive games. ... Grizzlies F Chandler Parsons played two seasons with the Mavericks from 2014-16 and averaged 14.8 points, 4.8 rebounds and 2.6 assists. Parsons was rested Wednesday night in Dallas. He finished the Thursday game with three points in 16 minutes.