Milton McCrory, the leading contender for the welterweight title of the injured Sugar Ray Leonard, remained undefeated in 20 professional fights with a unanimous 10-round decision yesterday in Detroit over Victor Abraham, Leonard's former sparring partner.

In a battle of Detroit lightweights, undefeated Greg Coverson won a unanimous 10-round verdict over Davey Armstrong in the second feature bout of the nationally televised card, hurriedly arranged to fill the void left by the pro football strike.

Coverson, continuing his drive for a hoped-for fight against Ray (Boom Boom) Mancini early next year, took command in the final two rounds to win his 29th fight and hand Armstrong only his second defeat in 23 bouts.

The judges scored McCrory's fight 98-91, 100-89 and 100-89.

"I thought that was the worst fight of my career," McCrory said. "It's hard to fight a guy like that. He never tried to bring the fight to me. I was really looking for a knockout because my other two fights went the distance."

McCrory, a 20-year-old Detroiter moving toward the title Thomas Hearns lost to Leonard in Las Vegas Sept. 6, 1981, carried the fight to Abraham, often trapping him in the corners and against the ropes.

With Leonard and Hearns sitting at ringside, McCrory solidified his No. 1 ranking by effectively using his 4 1/2-inch height advantage and superior reach to outpoint Abraham, 23-11.

"I'm too tall to get on the ropes and let him hit me," McCrory said.