"There was less swelling in there again," Nowitzki said. "The good news is it's not as much as it was last week in Barcelona.
"I guess that's a little positive, but I'm going to see if it does any better the next couple of days before I do another decision."
Nowitzki has been working through knee pain for almost all of training camp. The former first-round pick missed the last two preseason games because of the injury.
The surgery would put Nowitzki, 34, on the shelf for three to six weeks, he said.
Nowitzki has continually had problems in the same knee. He missed four games last season with soreness and swelling. He also had his knee drained twice last season.
The 14-year star played in 62 games for the Mavericks last season. He averaged 21.6 points per game and 6.8 rebounds per game -- his lowest marks since the 1999-2000 season.