Muhammad Ali was in an expansive mood last night before his 20th defense of the world heavyweight boxing title, over two reigns, against former Olympic light heavyweight champion Leon Spinks.

The champion acted as though a great burden had been lifted from his shoulders when he suddenly dropped his self-imposed vow of silence.

He was his old self in the lobby of the Hilton Hotel, where the fight will be held. He lured players from the gaming tables with his fimiliar routines about what he was going to do with his opponent.

He told the media earlier that he would not make a statement today that he was retiring because he had done that after other bouts and had not lived up to it.

Yet, he told crowds that gathered around him in the lobby that this might be his last fight.

Promoter Bob Arum is planning another tuneup bout for Ali in May, against eigher Bernardo Mercado of Columbia in Buenos Aires or Kallie Knoetze of Johannesburg in South Africa, before matching Ali against Ken Norton in September or October.

Arum has said that he has Ali under contract for a Norton bout. Rival promoter Don King arrived here yesterday and when he was asked how he figured in the sweepstakes for Ali's future services, admitted, "I'm out of it."

King is applying for a license to promote here and boxing commission chairman Johnny Mangiaracina says he will recommend that King be approved.

Arum has said that King plans to match Larry Holmes against Earnie Shavers here in May, but King says it probably will be next month. Ray Kelly, co-manager of record for Jimmy Young, said here that his fighter wants to fight the winner of Holmes-Shavers.

King has promoted most of Young's important bouts, as well as those involving Holmes.

Ali scaled 2241/4 pounds at the official weigh-in Tuesday and had a 24-pound advantage over Spinks