Dallas ? With the Dallas Mavericks on the brink of an epic meltdown, Dirk Nowitzki went to the gym and worked on his shot.

Not Nick Van Exel. He was too ashamed to leave his house.

“I went home and pulled down the blinds,” Van Exel said. “I didn’t want to be seen. It’s an embarrassing feeling to be up 3-0 and then lose three in a row. But this morning, we couldn’t wait.”

Nowitzki’s fine-tuned jumper produced 31 points, and Van Exel added 26, sending Dallas past Portland, 107-95, Sunday, finally eliminating the Trail Blazers after three failed attempts.

The Mavericks avoided a spot in NBA infamy by showing the tenacity they’d been lacking since winning Game 3. They drove the lane, banged for rebounds and prevented Portland from loading up on easy baskets.

The Blazers, who seemed to have the upper hand after manhandling Dallas in Game 6, ran out of answers in the fourth quarter. They failed to score a basket in the final 3:08, while the Mavericks made 13 of 17 shots in the period, including four three-pointers.

Nowitzki, who had four points and no rebounds in the 22-point loss in Game 6, led they way Sunday. After concentrating on rebounds the first half and scoring only eight points, he began looking for his shot during crunch time.

It was there, too, as he scored seven straight points starting with 2:52 left that put Dallas ahead for good. The capper was a 3-pointer that made it 100-94, drawing a roar from the crowd of 20,281 that was as much joy as relief.

Nowitzki celebrated by throwing up his arms, hugging Van Exel then catching Steve Nash as he leaped toward them. The Blazers’ slumped shoulders and blank faces indicated they were out of comebacks.

“We knew our energy wasn’t there in the last three games and that’s where we had to pick it up,” said Nowitzki, who had 11 rebounds. “We had to be more physical in the paint and rebound the ball. We worked hard all season to get the home-court advantage and we used that advantage today.”

Now they’ll have to try doing it all over again in the second round against the Sacramento Kings. Game 1 is Tuesday night in Dallas.

“This was a physically and mentally draining series,” said Michael Finley, who had 14 points and eight rebounds. “Nothing Sacramento can do will be tougher than what we faced here.”

Although Portland didn’t become the first NBA team to overcome a 3-0 deficit, the Blazers earned respect for becoming just the third team to stretch a series to seven games after losing the first three.

Whether it was the absence of Dale Davis (strained groin) or Scottie Pippen’s knee still not being at full strength, Portland lacked the moxie it showed the previous three games.

The Blazers rarely sustained runs, instead hanging tough mostly through tenacity. Dallas even matched them in rebounds with 42.

“We just couldn’t get it done. It’s a disappointment,” said Damon Stoudamire, who had 17 points and nine assists. “The last week has been fun. I think it’s shown a lot about the character, the heart that we have.”

Portland overcame a scoreless first half from Rasheed Wallace and Bonzi Wells and led 90-88 on a 3-pointer by Wallace with 4:43 left. Several players said an offensive foul on Arvydas Sabonis away from the ball with 2:12 left and Dallas up two was the turning point.

Pippen dribbled out the final 10 seconds, pounding the ball into the hardwood with his head down. As the buzzer sounded, he shook hands with Mavericks coach Don Nelson. The teams then lined up to congratulate each other on a tense, exciting finale — and series.

“By no means am I upset,” Portland coach Maurice Cheeks said. “It just showed we had players who care about playing, who care about winning and that we have a little more strength mind-wise than people think we do.”

Wallace scored 12 of his 17 in a row during the middle of the fourth. Sabonis had 16, eight in the opening minutes when covered by surprise starter Eduardo Najera, who is seven inches shorter. Zach Randolph had 14 points and 10 rebounds, Ruben Patterson scored 12 and Wells added 11.

Van Exel made 10 of 15 shots and either scored or assisted on Dallas’ first seven field goals of the fourth quarter. Nash had 21 points, seven assists and six rebounds.

With Dallas in jeopardy of flushing away the best season in its 23-year history — a 14-0 start, 60 wins — Nowitzki worked out Saturday even though the team was off after flying back from Portland.

He was looking to get back the stroke that produced 46 points in the opener and 42 in Game 3. He obviously found it.

“He’s unbelievable,” Van Exel said. “When you need a big basket, he comes up with it. His confidence right now is sky high.”

Notes: Portland fell to 8-4 in its red road uniforms. … This was the first time the Mavericks won a playoff series at home since beating Denver in the second round in 1988. That also was the only other seven-game series Dallas has ever won. … Good omen for the Mavs: Portland was ousted the last four years by the eventual champions.