The sources said Nowitzki plans to make his season debut in Thursday's road game against the Phoenix Suns, after a longer-than-anticipated recovery from spring surgery on his left ankle.
Nowitzki, the seventh-leading scorer in NBA history with 31,187 career points, was listed as questionable for the first time this season on Monday, but he sat out the Mavs' home win over the Atlanta Hawks.
"He's getting closer," coach Rick Carlisle said before the Mavs extended their home winning streak to 11 games with a 114-107 victory.
Nowitzki, 40, had hoped to be ready for the beginning of training camp but suffered a setback while playing in September pickup games. The tendon in his left foot flared up -- the result of increased flexibility due to the removal of bone spurs that had built up over years -- forcing Nowitzki to take several weeks off before working toward being well-conditioned enough to contribute.
In recent weeks, Nowitzki has been practicing with the Mavs, scrimmaging with player development interns and playing 3-on-3 after practices.
"Rhythm will be tough," Nowitzki said recently. "The last game I played was the end of March. Nobody just takes seven months, eight months off and comes out balling. It's going to be a process for me playing against NBA players, [especially] the speed of the game these days. It will take me probably a couple of games to get used to it, but we'll see how it goes.
"I'm not going to play 30 minutes anymore. Maybe get a couple of stints here and there and see how it goes."
Nowitzki is setting an NBA record for the longest career spent with only one team as he enters his 21st season with the Mavericks. Nowitzki and Los Angeles Lakers great Kobe Bryant are the only players in league history to play at least 20 years with one franchise.
Nowitzki, a 13-time All-Star who has won an NBA Most Valuable Player Award and been named NBA Finals MVP, has said he is approaching this season as if it will be his last, but he has been noncommittal about declaring that officially. He has repeatedly said he will not make a decision about retirement until after the season and does not want the spotlight of a farewell tour.
Nowitzki, who averaged 12.0 points and 5.7 rebounds in 24.7 minutes per game last season, will come off the Mavs' bench on a regular basis for the first time since his rookie season. Carlisle has the enviable challenge of blending Nowitzki into one of the league's most effective second units, with his minutes likely coming at the expense of fellow Wurzburg, Germany, native Maxi Kleber, who has the best net rating (plus-14.9 points per 100 possessions) of the 15-11 Mavs' rotation players.
"The boys are playing well," Nowitzki said. "Maxi's been playing, and Dwight [Powell]'s playing well off the bench. ... I have no idea [about the fit in the rotation], but it's not a bad thing to be deep at a position. It's a long season. Stuff always happens. Injuries always happen. It's good to have a deep team, like we've showed. Our bench has been great all year and has won a bunch of games for us."