OKLAHOMA CITY — The Oklahoma City Thunder beat the Memphis Grizzlies, 131-80, in Game 1 of their Western Conference playoff series Sunday, the fifth-biggest margin of victory in NBA postseason history.

Jalen Williams scored 20 points, and Chet Holmgren had 19 points and 10 rebounds.

Oklahoma City, which finished the regular season with a league-best 68-14 record, looked every bit the part of an overall No. 1 seed.

The Thunder’s Shai Gilgeous-Alexander, the league’s scoring champion with nearly 33 points per game, scored just 15. The Thunder still shot 50.5% from the field.

Ja Morant scored 17 points for Memphis on 6-for-17 shooting. Jaren Jackson Jr., who averaged just more than 22 points in the regular season, scored four points on 2-for-13 shooting. Marvin Bagley III also scored 17, but the Grizzlies shot 34.4% overall.

There have been two 58-point playoff margins in NBA history: Denver beating New Orleans, 121-63, on April 27, 2009, and the Minneapolis Lakers beating the St. Louis Hawks, 133-75, on March 19, 1956.

The Los Angeles Lakers beat Golden State by 56 (126-70) on April 21, 1973, and the Chicago Bulls beat the Milwaukee Bucks by 54 (120-66) on April 30, 2015.

And now, a 51-point game — where the Thunder had it well in hand by early in the second quarter.

This was Memphis’ first playoff game under interim coach Tuomas Iisalo. He coached nine NBA regular-season games before the play-in games.

Game 2 is Tuesday.