Dallas sent a contingent of owner Mark Cuban, coach Jason Kidd, president of basketball operations Nico Harrison, special adviser Dirk Nowitzki and assistant general manager Michael Finley to Slovenia where Doncic and agent Bill Duffy joined a press conference on Tuesday.

"It's a really special moment here. Thank you to Dallas for offering this... I never imagined this happening," Doncic said.

"I was only dreaming of playing in the NBA. Now I can sign an extension with the Dallas Mavericks for five more years."

Doncic's five-year extension kicks off in the 2022-23 season.

The two-time All-Star was visibly awed by the value of the deal as Kidd reminded him it was time to "get to work".

"It's a great sum, but I'm still not thinking about this," Doncic said.

"I have not bought myself anything worthwhile from this."

Doncic helped guide the Mavericks to back-to-back play-off appearances as Cuban continues to search for another championship.

Doncic was an All-Star in his second and third seasons after being named Rookie of the Year in 2018-19.

He's also been first-team All-NBA twice, which makes Doncic the first player eligible for a super-max extension off his rookie contract.

Cuban said the Mavericks envision a Hall of Fame career for Doncic "if not more, like Dirk (Nowitzki)".

Nowitzki set an NBA record of 21 seasons with the same franchise while becoming the league's sixth highest all-time scorer with the Mavericks.

Doncic has averaged 25.7 points, 8.4 rebounds and 7.7 assists in 199 games (all starts) for the Mavericks over his first three NBA seasons.

The Mavericks were this year eliminated in the first round of the play-offs by the Los Angeles Clippers in seven games - in which Doncic averaged 35.7 points, 10.3 assists and 7.9 rebounds for the series.

Doncic has signed the massive deal less than a week after leading Slovenia to the Olympics for the first time, where they were beaten by Australia in the bronze medal match.

Australian Associated Press