PORTLAND, Ore. -- It was "Welcome Back, Wesley Matthews" night at the Moda Center on Tuesday, but a teammate stepped up to steal the show.

Guard Deron Williams scored nine of his season-high 30 points in overtime as the Dallas Mavericks rallied for a 115-112 victory over the Portland Trail Blazers.

Matthews, who spent the previous five seasons with the Trail Blazers, was making his first appearance in Portland since signing a four-year, $70 million free agent contract last summer.

The veteran guard, who was greeted with a long standing ovation during pregame introductions, scored 11 of his 18 points in the fourth quarter and overtime.

Mavericks forward Dirk Nowitzki collected 28 points, seven rebounds and six assists. Center Zaza Pachulia had 14 points and tied his career high with 21 rebounds for Dallas, which trailed by seven points with 1:40 to go in regulation.

Williams, who scored 23 of his points after intermission and had a pair of big blocked shots in overtime, was the difference. He shot 11-for-17 from the field and also had eight assists and six rebounds with only one turnover in 45 minutes.

"He is really getting a feel for what is needed in our system," Dallas coach Rick Carlisle said of Williams, who played the previous five seasons with the Nets. "I told him in the fourth quarter I was going to try to get him a rest. And then during a timeout in overtime he said, 'Hey, where's that rest you were talking about?' We had a chuckle about it. I needed him in there."

Guard Damian Lillard totaled 25 points, 10 assists and eight rebounds, and forward Meyers Leonard scored a season-high 23 points for the Trail Blazers (7-12).

"A very disappointing loss," Portland coach Terry Stotts said. "That's a game we shouldn't have lost. We didn't make enough plays in the end to secure a win. You have to execute, and we didn't do it. It's too bad, because we did a lot of good things for 46 1/2 minutes."

Williams began the overtime with five straight points to give Dallas (11-8) a 101-96 lead.

Portland guard CJ McCollum sank a trey to cut the difference to 101-99, but Nowitzki answered with a short jumper to make it 103-99.

The teams traded baskets, but when Williams knocked down a 3-pointer, the Mavericks led 108-101 with 40.6 seconds left, and it was all but over.

Guard Gerald Henderson, who finished with a season-high 20 points, came off the bench for 12 second-quarter points as Portland seized a 52-50 edge at intermission. Nowitzki scored 13 first-half points, and Pachulia had 10 points and 13 rebounds before the break.

Portland pushed its advantage to 89-79 midway through the fourth quarter and still led 96-89 when Leonard sank a pair at the line with 1:43 to go.

Matthews scored on a rebound basket to trim the difference to 96-91 with 1:14 remaining.

Nowitzki brought Dallas within 96-94 on a 3-pointer with 47 seconds to play, then scored on a tip-in to tie the count at 96-96 with six seconds on the clock. Lillard's 3-point try at the buzzer bounced off the rim, and it was on to overtime.

"That's a tough loss to swallow," Leonard said. "We talk about the process a lot, but this is one we have to get. We flat-out should have gotten a win tonight."

Dallas started the game 8-for-10 from the field to grab a 20-5 lead midway through the first quarter. The Blazers, meanwhile, missed 11 of their first 13 shots.

Portland used an 8-0 run to draw within 20-13, but the Mavericks took a 27-18 advantage into the second quarter.

The Blazers produced a 7-0 spurt to cut the difference to 27-25. Dallas went on a 9-0 tear to go on top 44-32, but the Blazers came back with a 16-4 run to tie it at 48-48. Henderson's 3-point shot at the buzzer took Portland into halftime with a two-point advantage -- its first lead of the game.

NOTES: Portland G Damian Lillard, who played only 17 minutes in a 102-87 loss to the Los Angeles Clippers on Monday night due to abdominal pain, went 41 minutes against the Mavericks. "He's not 100 percent," coach Terry Stotts said before the game. ... Dallas won despite having its reserves outscored 73-16. ... Portland F Ed Davis had 10 points and 11 rebounds for his fifth double-doubles this season, the most by a reserve player in the league. ... Dallas G J.J. Barea (ankle) missed his third straight game, and F Chandler Parsons (knee) sat out, too. ... The teams entered the game averaging exactly the same in scoring -- 100 points per game.