And for the first time since 2000, the San Antonio Spurs are not.

Dirk Nowitzki scored 31 points in his first breakout game of a lopsided series, and the Mavericks won a playoff series for the first time in three years by eliminating the Spurs in five games with a 106-93 victory on Tuesday night.

Besides closing another chapter between the Texas rivals, this series seemed to signal more: that the Mavericks are much better than their No. 6 seed might suggest, and whether the Spurs are slipping into a new stage after winning four NBA titles in the past decade.

"(We) went through a lot this year, a very turbulent year," Mavericks coach Rick Carlisle said. "Injuries. Ups, downs, emotional stuff, and we really stuck together. We came together at the right time."

The Mavericks advance to the Western Conference semifinals to play either Denver or New Orleans. The Nuggets lead that series 3-1 and can finish off the Hornets on Wednesday at Denver.

Tim Duncan scored 30 and Tony Parker had 26 but again got little help - the story of the series for the two-dimensional Spurs. Predictions that the Spurs were doomed while Manu Ginobili sat out the playoffs with a bum ankle appeared largely validated, as San Antonio never got anyone to step up in his absence.

For Duncan, it's the first time in his career he couldn't lead the Spurs past the opening round.

"They had more firepower than us. They played better than us," said Duncan, who never played in San Antonio's first-round loss in 2000 because of a knee injury. "However you want to put it, obviously they were the better team this year. That's all you can say."

Getting to the West semifinals is a dramatic turn for the Mavericks, who were a borderline playoff team as late as March and got a public lashing from owner Mark Cuban after a listless loss to woeful Oklahoma City. Dallas pulled together to win seven of nine entering the playoffs, and has now won 11 of its last 14.

The Mavs can also stick this to their Interstate 35 rivals: only twice in the Duncan era have the Spurs been eliminated on their home court, and both have came courtesy of Dallas.

Howard rang in his 29th birthday with 17 points, and may have permission from Carlisle to celebrate this time. Howard enraged former coach Avery Johnson last year when he didn't cancel his birthday plans despite a blistering Mavs playoff defeat, but the party may be on coach Carlisle after this series win.

"I think (Howard) probably is our MVP of the series," Carlisle said. "He played great. He was there for us - a lot of big plays that didn't necessarily lead to scores."

Howard's biggest gift to the Mavs: a momentum-changing 3-pointer with 4:20 left in the third, which he celebrated by skipping down the sideline and razzing the crowd. When Jason Kidd hit another 3-pointer at the buzzer in the third, his teammates jumped from their seats and spilled onto the floor.

They could sense the victory, and the Mavs put it away in the fourth having never trailed. Terry finished with 19 points and Nowitzki finally emerged after four relatively pedestrian games.

"The big key for me was I got into a good rhythm right away," Nowitzki said. "Made some shots, had some good looks right away, and that usually helps get the confidence up and I was able to carry through."

The Spurs, meanwhile, end their season the same way it started: plenty of Parker and Duncan, but not much else. After combining for 75 percent of San Antonio's points in a Game 4 loss, the duo were again the only Spurs in double figures.

San Antonio lumbers into the offseason facing questions about where its team, the NBA's winningest over the last decade, goes from here. Along with the flourishes of another Southwest Division title and 10th consecutive season with 50-plus wins, there was also the ignominy of scoring the fewest points in Spurs playoffs history in a blowout Game 3 loss.

The Big Three will be back next year for the Spurs, piloting what is now a championship drought by their standards: San Antonio has been a denied an NBA finals trip the past two seasons, its longest lapse since the gap between their 1999 and 2003 titles.

"The Mavs beat the Spurs," coach Gregg Popovich said. "They're the best team, and that's that."

Notes: The AT&T Center took some precautions against the spread of swine flu, setting up hand sanitizer stations around the arena and arming ushers with wipes for fans who wanted them. There are three confirmed cases of the virus near San Antonio. ...The Mavericks shot 13 free throws in the first half to San Antonio's two. This season, the Mavs were 28th in the NBA in free throw attempts. ... Spurs F Drew Gooden, acquired during the season for the postseason push, didn't play.