The Dallas Mavericks are locking up star guard Luka Doncic with the first-ever supermax rookie contract extension. ESPN reports it's a five-year deal worth 207-million dollars, making Doncic the first player in NBA history to earn the supermax rookie extension. He became eligible after being named to the All-NBA First Team twice in his first three seasons in the league. The Mavs' brass flew to Slovenia on Monday to formally present the contract to the 22-year-old. Doncic is expected to officially sign the deal and hold a press conference on Tuesday.