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

The 51-point margin was seven points shy of the record and was the largest Game 1 win in NBA playoff history.

Aaron Wiggins scored 21 points, Jalen Williams scored 20 points and Chet Holmgren had 19 points and 10 rebounds. 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.

“We played to our identity,” Gilgeous-Alexander said. “Nothing more, nothing less than that. We were who we were all year ... and it’s going to be the key to our success, just staying true to who we are.”

Gilgeous-Alexander had said several times since Oklahoma City’s loss to Dallas in last season’s Western Conference semifinals that he would be intentional about getting his teammates better prepared for this postseason.

Ja Morant scored 17 points for Memphis on just 6-for-17 shooting. Jaren Jackson Jr., who averaged just over 22 points in the regular season, scored four points on 2-for-13 shooting.

The Thunder, who finished the regular-season with a league-best 68-14 record, took control with a 20-0 run that gave them a 55-22 lead in the second quarter.

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

Celtics 103, Magic 86 >> Derrick White scored 30 points, Jayson Tatum had 17 points and finished the game after a scary late fall, and Boston beat Orlando in Game 1 of their first-round playoff series.

Payton Pritchard added 19 points off the bench for Boston, which hosts Game 2 on Wednesday night. Jaylen Brown played 31 minutes and had 16 points on 6-of-14 shooting after missing the final three games of the regular season due to a lingering knee issue.

With Boston leading 89-73 with 8:28 remaining, Tatum went up for a dunk and was hit hard by Kentavious Caldwell-Pope as he tried to block it. Tatum landed awkwardly on his right side.

He stayed down briefly before eventually rising to his feet, clenching his right hand. After a video review by referees, Caldwell-Pope’s foul was upgraded to a flagrant foul. Tatum subsequently missed the two ensuing free throws but remained in the game.

Paolo Banchero led the Magic with 36 points and 11 rebounds. Franz Wagner added 23 points for Orlando, which has not made it out of the first round of the playoffs since the 2009-10 season.