THE OTHER FIGHTS : Chavez Stops Duplessis; Brown Wins; Duran Quits

Julio Cesar Chavez knocked down John Duplessis in the second round and then sent him through the ropes at 2:42 of the fourth round in an easy defense of his World Boxing Council and International Boxing Federation junior-welterweight titles Monday night at the outdoor arena at the Mirage hotel.

Actually, Duplessis (36-2) might have been trying to jump out of the ring.

Duplessis started out running fast laps around the ring, but slowed down after Chavez (73-1 or 74-0, depending on whose record is used) began whacking him in the ribs with the short, unerring hooks.

Now, it looks as if Chavez’s next fight will be in court. Rival promoters Don King and Bob Arum both claim promotion rights to the champion from Culiacan, Mexico.

Simon Brown became both the International Boxing Federation and World Boxing Council welterweight champion when he stopped Maurice Blocker in the 10th round.

Brown, a longtime Washington, D.C., gym pal of Blocker’s, knocked Blocker down with a powerful left hook.

Blocker (32-2) got up, but when Brown (34-1) hurt him again late in the 10th, referee Mills Lane stopped it at 2:10.

Roberto Duran, fighting at 168 pounds, started off the evening with a replay of his no mas 1980 fight with Sugar Ray Leonard.

Duran, 39, was behind on points to San Francisco’s Pat Lawlor (15-1) when he quit after doubling up in pain 1:50 into the sixth round.

Duran is 86-9.