Ellis scored 22 points, and the Bucks spoiled Nowitzki's first game since April 2003 with at least 20 points and 20 rebounds in a 95-90 victory over the Mavericks on Tuesday night.
Playing point guard with struggling backcourt mate Brandon Jennings on the bench, Ellis twice put the Bucks ahead in the final 2 minutes, the last time on a jumper for a 92-90 lead with 1:03 remaining. Milwaukee snapped a three-game losing streak -- all by three points or fewer, just the third time that's happened in franchise history.
"We can put that behind us now and build off of that," said Ellis, who also had game highs with nine assists and six steals.
Nowitzki had 21 points and 20 rebounds for the Mavericks, who had two chances to tie after Ellis' go-ahead basket. Vince Carter missed a 3-pointer, and after Nowitzki's 20th rebound at the other end, Darren Collison's wild shot on a drive wasn't close.
The Mavericks, who have made the playoffs 12 straight years, fell five games behind Houston for the final postseason berth in the Western Conference with 26 games remaining. Dallas had a chance late in its last three losses in a season full of close defeats.
"It's not looking good for sure," said Nowitzki, who had 25 points and 22 rebounds against the Lakers in his fifth 20-20 game on April 3, 2003. "This league is crazy and I've seen a lot happen. But it's definitely getting tight. If we want to make a push, we have to find a way to win those close games."
J.J. Redick, playing his second game in Dallas in six days but in a different uniform after he was traded from Orlando to Milwaukee, had nine points at halftime, tied with Mike Dunleavy for the team lead, and finished with 14. Dunleavy had 13.
Redick stayed on the floor with Ellis in the final minutes, with Jennings watching after scoring eight points on just 3-of-11 shooting.
"I just felt like that group was playing well together," Bucks coach Jim Boylan said. "I saw the game kind of slipping from us a little bit and felt I needed to get those guys out there again."
Larry Sanders had 11 of his 13 points in the second half and led Milwaukee with 13 rebounds.
The Mavericks had four chances to break an 88-all tie with less than 3 minutes left, but Nowitzki turned it over after three straight misses and offensive rebounds. The Mavericks shot 42 percent and were 1 of 17 from 3-point range.
O.J. Mayo, Dallas' leading scorer, bounced back with 18 points after scoring just eight on 2-of-9 shooting while Kobe Bryant dominated with 38 in the Lakers' win Sunday. Elton Brand had 12 points and 14 rebounds.
Dallas led 88-83 after a jumper by Nowitzki, but Ellis answered with a three-point play and Dunleavy scored on a layup off a turnover by Nowitzki -- Ellis' sixth steal and one of 20 Dallas turnovers -- to tie the score at 88.
"We built two or three eight-point leads and then proceeded to immediately let those leads go away," said Dallas coach Rick Carlisle. "The inability to sustain has been our nemesis all year."
The Mavericks went on an 8-0 run to finish the third quarter and erase what was Milwaukee's biggest lead to the point -- four. Brand had a pair of jumpers and Nowitzki and Mayo had one apiece while the Bucks went the last 4 minutes of the quarter without scoring.
The last six minutes of the first half were a series of runs that ended with Dallas leading 49-44. Led by six from Brandan Wright, the Mavericks went on a 14-2 spurt for a 41-31 lead before the Bucks scored 10 straight to pull even.
Dallas went on an 8-0 run started by two buckets from Collison, who led the Mavericks with 11 points and four assists before halftime, but Dunleavy hit a 3-pointer with 2 seconds left to pull the Bucks within five.
Drew Gooden, who hadn't played in six games and sat out 15 of the previous 16, had eight points in the first half for the Bucks, one shy of his season high. He was the Milwaukee TV crew's choice for the halftime interview before going scoreless in the second half.
The Bucks suspended C Samuel Dalembert for the Dallas game for an unspecified violation of team policy. He was relegated to a backup role after the emergence of Sanders, although he did have 35 points, a career high, and 12 rebounds off the bench Feb. 5 against Denver. ... Mavericks G Anthony Morrow played just the final 3.9 seconds in Sunday's loss to the Lakers, his first game in uniform after coming over in a deadline trade with Atlanta. He got in the first quarter against the Bucks, and was 0 of 2 from the field in 3:41. ... Nowitzki drew a duck and a scowl from Carlisle when an errant baseball pass on an inbound play flew over Carlisle's head out of bounds for a turnover 29 seconds into the game.