Nowitzki was expected to meet Saturday with Mavericks officials after having a night to sleep on a proposal from the club.
Team officials could not be reached for comment.
Nowitzki opted out of the final year of his contract to become an unrestricted free agent for the first time.
Dallas could offer him more than any other team, a maximum of four years for $96 million with a no-trade clause. On Friday, team president Donnie Nelson said the club's proposal was "significant."