Shams Charania of Yahoo Sports reported the update Thursday, but noted "neither side appears in [a] rush" to finalize the deal, since the Mavs legend isn't actively seeking other opportunities as a free agent.
The New York Times' Marc Stein previously reported Nowitzki and the Mavericks mutually agreed to decline his $5 million team option for the 2018-19 season to pursue a new contract so Dallas could open up more cap space in advance of free agency.
However, there's never been any doubt about the two sides reuniting.
Nowitzki announced in April he planned to return for a 21st season, and he later confirmed he would keep an open mind about extending his stay in Dallas beyond the 2018-19 campaign.
"I think I guess at this age you kind of take it one year at a time," the 40-year-old told Dwain Price of the team's official website. "It sounds cliche, but that's how it is—see how I come through (next year). ... I still enjoy it, I still enjoy competing, I enjoy going out there helping the team compete. If I wouldn't have fun doing it anymore and competing, then it's time to go."
Last season, Nowitzki averaged 12.0 points and 5.7 rebounds on 45.6 percent shooting from the field, including 40.9 percent from three while logging 24.7 minutes per game—the fewest since his rookie season.
If Nowitzki maintains that efficiency in the scoring column next season, he will make some serious history. As things stand, the future Hall of Famer is 232 points away from passing Wilt Chamberlain for fifth on the NBA's all-time scoring list.
Once Nowitzki (31,187 points) passes Chamberlain, his next task will be to vault ahead of Michael Jordan (32,292 points) and settle in at No. 4 all-time behind Kobe Bryant.
Beyond impending achievements, Nowitzki should continue to serve as a mentor to the likes of Dennis Smith Jr. and Luka Doncic as the Mavericks attempt to begin their ascent up the Western Conference standings.