DALLAS — Luka Doncic scored 25 of his 29 points in the first half, Kyrie Irving added 21 points and the Dallas Mavericks emphatically extended their season on Friday night, fending off elimination by beating the Boston Celtics 122-84 in Game 4 of the NBA Finals.

The Mavs’ stars were done by the end of the third quarter, with good reason. It was all Dallas from the outset, the Mavs leading by 13 after one quarter, 26 at the half and by as many as 38 in the third before both sides emptied the benches.

The 38-point final margin was the third-biggest ever in an NBA Finals game, behind only Chicago beating Utah 96-54 in 1998 and the Celtics beating the Los Angeles Lakers 131-92 in 2008.

Before Friday, the worst NBA Finals loss for the 17-time champion Celtics was 137-104 to the Lakers in 1984. This was worse. Much worse, at times. Dallas’ biggest lead in the fourth was 48 — the biggest deficit the Celtics have faced all season.

The Celtics still lead the series 3-1, and Game 5 is in Boston on Monday.