The Mavericks (50-32) have been locked into the seventh seed in the Western Conference for a week. They had to wait until the final night of the regular season to find out their opponent, which was settled with the Rockets' 117-91 win over Utah and San Antonio's 108-103 loss to New Orleans.
The Blazers (51-31) have the fourth seed as Northwest Division champions but will open the postseason on the road against the No. 5 seed, either San Antonio or Memphis.
LaMarcus Aldridge led Portland with 19 points after missing two games with a left foot sprain.
Aldridge treated the otherwise meaningless game as a way to get back in rhythm. Dallas had the rationale of chasing 50 wins for the first time since taking the title in 2011. Otherwise, both teams were more concerned with what was happening elsewhere.
The former Dallas-area high school star wanted to play close to regular minutes after missing two games. Aldridge has already played about half the season with ligament damage in his left thumb that will require surgery in the offseason.
"When you try not to get hurt, that's when you get hurt," Aldridge said earlier in the day. "I knew I was going to at least play this game when we left on the road trip. I wanted to have that as a final tuneup game and keep my wind."
Nicolas Batum (right knee), CJ McCollum (sprained left ankle) and Chris Kaman (back) sat for Portland after getting injured Monday in Oklahoma City. Dorell Wright (broken left hand) and Arron Afflalo (right shoulder strain) aren't expected back until the playoffs.
For Dallas, Chandler Parsons missed his sixth straight game with a right knee injury, and Devin Harris was sidelined after injuring his left big toe Monday against Utah.
But all the other regulars played. Chandler had his 31st double-double -- the most since he had 38 with New Orleans in 2007-08 -- while Dirk Nowitzki had 16 points and Monta Ellis added 15.
"I don't know how you tune up if you're not trying to win," Dallas coach Rick Carlisle said before the game. "Probably not a very useful exercise to be out there if you're not going for it."
Trail Blazers: Damian Lillard had 17 points, and Steve Blake added 14 with 4-of-7 shooting on 3-pointers. ... Seldom-used rookie guard Tim Frazier matched his career high with 13 points and had 10 assists.
Mavericks: Dallas secured its first 50-win season since the last of 11 straight that culminated with the franchise's first championship four years ago. ... Amare Stoudemire had 13 points and six rebounds.
Trail Blazers: at either San Antonio or Memphis in the playoffs, Saturday or Sunday.
Mavericks: at Houston, Saturday or Sunday.