DALLAS (AP) -- 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."
Boston has lost four in a row, and six of seven.
"We've got to get our guys back. At one point, I had had five guards out there. We were just trying to mess up the game," coach Doc Rivers said. "I'm scared to talk to the medical staff because they don't give me good news. We've got to hold the fort until we get bodies back."
Rivers didn't have an update on O'Neal or Wilcox after the game.
Nowitzki scored all of Dallas' points in a 10-2 run midway through the second quarter that pushed the Mavericks ahead by 14. They led by double digits the rest of the way.
At No. 19 on the scoring list is Garnett (23,719), who missed his second consecutive game for personal reasons.
Jason Terry added 16 points with four 3-pointers for Dallas, and Shawn Marion had 11 points.
Jason Kidd, who began the game tied with Michael Jordan for second on the NBA career list for steals, had three against the Celtics to push his career total to 2,517. Kidd is also second in career assists.
"Listen, every week we're going to have records broken with the guys we have on this team. It's like a legends team," Carlisle said. "Jason Kidd's career has been amazing. Think about 18 years, almost two decades, of top-notch excellence."
Ray Allen added 15 points for Boston, and Avery Bradley had 12.
Rondo was suspended two games without pay by the NBA after throwing a ball at an official during Sunday's loss at Detroit. He received two technical fouls and ejected from a game for the first time in his professional career.
Bass, a former Mavericks player who is one of Boston's top reserves, was inactive for the fifth consecutive game because of a sore left knee.
Dallas was already up 44-34 at halftime against the Celtics when Wilcox picked up his fourth foul on Boston's first offensive possession of the second half. It wasn't clear when or how he got hurt, but he was out before the end of the third quarter.
Kidd then hit a 3-pointer before Nowitzki's step-back 13-footer made it 49-34.
The Mavs built as much as a 24-point lead, though Boston cut that to 15 before Marion's left-handed tip-in of a Lamar Odom miss at the end of the third quarter.
"Coming off of (Sunday's loss), the guys were really up for this," Carlisle said. "Sometimes you have a letdown when a team is missing a couple of star players. We did a good job of not letting that happen, playing with consistency from start to finish."
NOTES: Dallas swept the season series against the Celtics for the second season in a row. ... Both teams play their final games before the All-Star break on Wednesday. The Mavericks are home against the Lakers. Boston plays at Oklahoma City.