DALLAS -- The second makeover of the Dallas Mavericks in as many seasons just got tougher.
Star forward Dirk Nowitzki had arthroscopic surgery on his ailing right knee Friday and the 11-time All-Star isn't expected to resume on-court activities for about six weeks.
Dallas opens the regular season in 11 days at the Los Angeles Lakers.
"It's never going to be easy to lose a game-changer for six weeks," Mavericks coach Rick Carlisle said. "We're going to have to make up for it in other areas."
The 34-year-old Nowitzki has experienced swelling in the knee most of the preseason, twice having the knee drained since training camp started Sept. 29. The knee didn't improve after rest, ice and light conditioning work, leading to the decision to have surgery.
The 2011 NBA finals MVP played just one preseason game -- the opener in his native Germany.
The Mavericks already have the challenge of working five new players into the rotation, and one of them can play Nowitzki's position -- 13-year veteran Elton Brand. Vince Carter, another veteran who joined Dallas last season, also could slide into that spot.
The Mavericks were never much of a threat to defend their 2011 title last season after deciding not to bring back several key contributors. On top of the roster shuffling, Nowitzki had conditioning trouble and a sore right knee early in the season and eventually sat four games. He didn't miss any more time after that.
This is likely to be the most extended absence of Nowitzki's career. He's never missed more than nine games in a season.
"I'm sure you're all not expecting us to be good now, so where is the pressure?" Carter said. "Nobody's giving us a chance with or without him, so for us we've just got to play and let the chips fall where they may."
Nowitzki is the franchise's career leader in points and has averaged 22.9 points and 8.3 rebounds in 14 seasons.