Aldridge, a former Dallas-area high school star who finished with 25 points and 12 rebounds, made the fallaway jumper over the outstretched arm of Mavericks 7-foot center Brendan Haywood at the overtime buzzer, then was mobbed by teammates at center court.
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"LaMarcus is our All-Star," Portland interim coach Kaleb Canales said. "We were going to LaMarcus. Big-time player, big-time shot."
The Mavericks won the previous meeting between the teams this season, 97-94 in two overtimes on Feb. 11 in Dallas.
"This is big because it was in the crib (his hometown)," Aldridge said.
Raymond Felton scored 16 of his season-high 30 points during Portland's 30-10 surge in the third quarter. Jamal Crawford added 14 points for the Blazers, who've won four of six to remain in playoff contention with 10 games left.
"The last time we were here it was a tough loss," Crawford said. "(A loss) tonight would have definitely clouded our playoff hopes."
With the score tied at 97 in the final minute of overtime, Felton misfired on a long 3-pointer, and Nowitzki grabbed the rebound. However, he threw the ball out of bounds while trying to pass to a wide-open Shawn Marion streaking downcourt with 19 seconds left.
That gave the Blazers possession, leading to Aldridge's game-winner and a confidence boost for a team that entered the night 7-19 on the road.
"It was just a brutal play," Nowitzki said of his bad pass. "I got the rebound, and I really wanted to hold it for the last shot. I looked up and saw Shawn was wide open. I tried to rush it to him, and it just got away.
"It was kind of an instinct play. You see a guy open, you want to throw it to him. Sometimes you make decisions in a split second. I made the wrong one."
Terry kept his team close in the fourth quarter, hitting two 3-pointers, then feeding Marion for a layup with 15.6 seconds left in regulation to tie it at 91.
The Blazers set up for a final shot with 8 seconds remaining, but Terry stole the ball from Crawford before missing a desperation 3 at the buzzer, sending the game to overtime.
Portland trailed by 15 in the second quarter, but the Blazers finished the third with a 16-0 run that included 12 from Felton, who had three 3s and a three-point play during the spurt.
Felton's swish from beyond the arc with 0.8 seconds left in the third gave him 26 points and put Portland ahead 74-66.
Felton's previous season-high was 24 on March 25 against Golden State.
"A couple of their guys got going, and it was tough to shut them off," Marion said.
Nowitzki got off to a strong start, hitting his first four field goal tries and scoring 10 of his team's first 14 points.
Dallas was in front 27-17 heading into the second quarter and was up at halftime, 56-44.
The Mavs had won 22 of their previous 29 regular-season meetings with the Blazers.
Terry's 3-pointer in the first quarter gave him 1,761 for his career, passing former Dallas teammate Peja Stojakovic for fifth on the NBA's all-time list. ... Dallas reserve C Ian Mahinmi missed the game to be with his financee for the birth of their child. Mahinmi is expected to rejoin the team for Saturday night's game at Memphis. ... Mavs starting G Delonte West had been questionable after twisting his left ankle by stepping on a ball during Friday morning's shootaround, but West underwent treatment and was in the lineup. ... The Mavericks were already short-handed with G Jason Kidd sitting out his third consecutive game due to a strained right groin. ... Canales is 7-6 since taking over after the firing of Nate McMillan on March 15. Calales is a native of Laredo, Texas, and a graduate of the University of Texas-Arlington.