After not being able to run back on defense, Doncic left the floor during a timeout with 10:20 remaining in the first quarter. He hobbled to the locker room for further evaluation. X-rays were negative, the team announced.
"Luka Doncic will not travel to Milwaukee due to a right ankle sprain," Mavs coach Rick Carlisle said in a text message to several reporters Sunday. "He will stay in Dallas with [Mavs director of player health and performance] Casey Smith and receive treatment. There will be no further updates until Wednesday night."
Doncic, the Rookie of the Year last season, has established himself as an early MVP candidate. The 20-year-old was averaging 29.3 points, 9.6 rebounds and 8.9 assists per game entering Saturday night and leads the league with eight triple-doubles, including a 41-point performance in Thursday's win over the Detroit Pistons.
Doncic's streak of 20 consecutive games with at least 20 points, five rebounds and five assists ended because of the injury. Only Oscar Robertson had a longer such streak in NBA history.
The timing of Doncic's injury is especially tough for the Mavs, who had won 11 of their previous 13 games. The Heat were the first of five consecutive Eastern Conference powers the Mavs will face, with the Milwaukee Bucks, Boston Celtics, Philadelphia 76ers and Toronto Raptors on Dallas' schedule over the next eight days.
Backup point guards Jalen Brunson and J.J. Barea will likely have their roles expanded while Doncic recovers. Brunson and Barea combined for 30 points, nine rebounds and 13 assists in the loss to the Heat, when the Mavs rallied from a 24-point deficit to force overtime. Reserve guard Delon Wright could also play an expanded role, but he played only nine scoreless minutes Saturday in his return after missing a week because of a strained right adductor.
"There's going to be opportunities and a lot of touches for a lot of people," Barea said Saturday. "We've got to be ready."