DALLAS

Dirk Nowtizki and the defending champion Dallas Mavericks seem to be hitting their stride at the midway point of their season.

The short-handed Boston Celtics are just struggling.

Nowitzki scored 26 points with season- high 16 rebounds while moving into the top 20 on the NBA career scoring list, and the Mavericks never trailed in an 89-73 victory over Boston on Monday night.

“I always say that it’ll be great to look back (at milestones) when my career is over. Right now, I feel better and got to keep it going,” Nowitzki said. “Ever since I took the week off, I feel better and I’ve been moving better. I’ve got to keep attacking.”

A night after scoring a season- high 34 points against the New York Knicks, Nowitzki moved to No. 20 on the NBA scoring list with seven points in the first quarter against Boston. That pushed him one past Hall of Famer Robert Parish (23,334), who played 14 of his 21 NBA seasons for the Celtics.

After finishing with his 26 points in 31 minutes, Nowitzki’s career total was at 23,354 points. All of those have come the past 14 seasons, all with Dallas. Nowitzki, who is set to play in his 11th consecutive All-Star game this weekend, also eclipsed 1,000 career blocked shots.

“For those people that didn’t think he was a top 20 all-time player, this is good evidence of that. You can’t have that accomplishment without a remarkable level of sustained excellence,” coach Rick Carlisle said. “The other great thing right now, he continues to do better physically. He’s moving every game seemingly better. We’ve got to keep building on that, too.”

Since getting a four- game break last month to strengthen his sore right knee and improve his game conditioning, Nowitzki is averaging 21.7 points the last 13 games. The Mavs are 9-4 in that stretch, including a season-best winning streak of six games before Sunday’s loss against the Knicks.

Already without suspended Rajon Rondo, absent Kevin Garnett and injured Brandon Bass, the Celtics lost starters Jermaine O’Neal (sprained left wrist) and Chris Wilcox (right adductor strain) in the third quarter.

“It’s real tough when you’re put in that situation,” said Paul Pierce, who led the Celtics with 20 points. “It’s just been bad luck lately.”