Deron Williams’ ninth assist was the biggest Tuesday night.

With less than 15 seconds left on the clock and the Dallas Mavericks trailing by two, D-Will drove straight into the teeth of the Chicago Bulls defense. After drawing two defenders in the paint, No. 8 found the open man: Wesley Matthews for the deciding 3-pointer in Dallas’ 99-98 win on the road. The Matthews trey gave the Mavs the lead for good, and it came just seconds after Chicago’s star swingman, Jimmy Butler, hit a clutch jumper to put the home team on top.

“Jimmy came down and made a great play. He went over the top of me and shot,” Matthews said. “And I can’t really take much credit for the other end of the court. D-Will came down in transition. I think everyone was expecting a timeout, which was a good play by Coach to not do that. D-Will made a great play, he found me, and I just had to knock it down.”

Dallas Mavericks v Chicago Bulls

No. 8 finished with 11 points, nine assists, six rebounds and one key steal. In the opening stanza, D-Will had two assists and five points, including one make from 3-point range, but the Mavs carried a four-point deficit into the second quarter.

Dwight Powell sparked a run for Dallas early in the second, and the Mavs held a 39-35 lead when Deron checked back in at the 7:13 mark. The Mavs point guard helped to keep the rally going, feeding Harrison Barnes on a jumper just 12 seconds after returning to the floor. The Bulls battled back to within two, but No. 8 capped a 7-2 Dallas rally to close the third with the Mavs on top, 54-47.

They kept it going early in the third. Deron dropped dimes back-to-back to Matthews for a three and to Barnes for a tough bucket on the interior. Chicago immediately called timeout to quell the Mavs rally, which put them ahead by 13, 64-51. The Bulls then scored four straight, but D-Will kept them at arm’s length with a dish on a Seth Curry trey and an 18-foot jumper himself. The Mavs led by 10, 69-59, when he checked out at the 4:18 mark.

The Bulls closed the third strong, using an 8-2 run to cut the Dallas lead to just two to start the fourth, setting the stage for a thrilling final frame.

Dallas Mavericks v Chicago Bulls

A J.J. Barea three pushed the Dallas lead to five before the Bulls ran to an 88-85 advantage. But D-Will came through with a clutch sequence, feeding Seth Curry for a long 2-pointer and poking away a Rajon Rondo pass to set Barnes up for a fast-break dunk, putting the Mavs back ahead 89-88.

The Bulls then countered with a 4-1 spurt, forcing D-Will back into action. The Illinois Fighting Illini great recorded assist No. 8 on a Barnes trifecta with 3:02 to go. On the very next possession, he corralled a Nikola Mirotic miss and used a crafty move to get past the big man down low on the other end of the floor, scoring underneath to give the Mavs a 95-94 lead.

The contest was tied at 96 when Butler hit a tough jumper over Matthews to give the Bulls a late lead, but the Dallas guard duo one-upped Chicago’s franchise player. D-Will went right at Mirotic again, and when Dwyane Wade came to help, No. 8 kicked it out to a wide-open Matthews, who buried the game-winning three.

Matthews then pressured Butler on the other end, forcing him to pass it into the corner to Wade. D-Will was there trapping his fellow Olympian, forcing him to take a difficult fallaway jumper, which missed its mark as the buzzer sounded.

“We’ve been struggling, it’s been tough for 2 1/2 months, but guys kept hanging in and believing in each other,” coach Rick Carlisle said. “Games like this give us even more confidence.”

NEXT UP

The Mavs will put their three-game win streak on the line against another tough Eastern Conference opponent, Thursday night at the Miami Heat.

This is the first of two meetings between the Heat and the Mavs this season. Miami, then led by Wade, swept Dallas in two games last season. For his career, Deron has averaged 14.9 points, 7.9 assists and 2.7 rebounds against the Heat.

Tipoff is set for 6:30 p.m. CT Thursday night from American Airlines Arena.