Mavericks superstar Luka Doncic sustained a moderate right ankle sprain Saturday in the opening minutes of Dallas’ 122-118 overtime loss to the Miami Heat, league sources told ESPN’s Adrian Wojnarowski. X-rays on the ankle were negative, the team said. “We hope it’s not serious,” said Mavs coach Rick Carlisle, who added that he does not expect Doncic to be available Monday night for a road game against the Milwaukee Bucks. “That’s about all that we have for you now.”