Nowitzki said he doesn't know why the swelling keeps coming back and that arthroscopic surgery remains an option if it keeps happening.
"I'm not going to play on a swollen knee all season," Nowitzki said. "So I think if it comes back a couple of more times, we'll definitely have to look at something else."
It is the same knee and same issue Nowitzki dealt with early last season. The Mavericks held their perennial All-Star out for a four-game stretch in January to improve his game conditioning and give him time to strengthen his right knee.
The only real difference this time, according to Nowitzki, is that his leg strength is really good.
"Hopefully it will be OK from here on out," he said.
The 34-year-old Nowitzki, who is going into his 15th NBA season, said he would keep working and see how the knee responds over the weekend. The Mavericks scrimmage Saturday as part of a fan day, then practice Sunday before their first preseason game at home Monday night.
Nowitzki didn't play in the Mavericks' loss Tuesday against FC Barcelona Regal in Spain.
Coach Rick Carlisle said Nowitzki was held out of that game after the 7-footer had an "awkward movement" in practice the coach said might have triggered the swelling. The coach didn't elaborate on what that movement was.
"We're looking at it very closely," Carlisle said after practice. "He did a good job today, and we'll see where things are at with each day."