Isaiah Hartenstein had 16 points and 12 points — and scored Oklahoma City’s only two field goals of the final 8:28 — as the Thunder withstood a furious Dallas rally to beat the Mavericks 101-94 on Monday night to improve to 4-0. Shai Gilgeous-Alexander scored 23 points to lead the defending NBA champions. Chet Holmgren had 18 points, 11 rebounds and four blocks.