Costello, then 19, wandered into the local YMCA gym and laced on the gloves for the first time. Youthful, aggressive and strong, he learned to swing hard from both sides and developed into a champion amateur fighter. He had a 40-7 record, including a stunning knockout victory in the 135-pound open finals of the 1978 New York Golden Gloves. That night, following his fight, he joined his high school sweetheart, Jane—they have since married—in the stands. She just happened to be sitting in front of Mike Jones, at that time the co-manager of lightweight Howard Davis and heavyweight Gerry Cooney. Jones had seen Costello fight and handed him a card, which the fighter stuffed nonchalantly in a pocket.
"I never thought I'd hear from him again," Jones says. Nonetheless, Costello called nine months later and asked Jones to be his manager. Jones turned Costello over to Valle, who was also training Cooney, and the three partners were on their way. It was a long way, too. Costello came to Valle rough and raw. "He was always a natural puncher, but he didn't know defense, how to get off the ropes," says Valle. "His punches were stiff, and his leg movement was poor."
Costello fought mostly near New York City—White Plains, Kingston, Atlantic City, Long Island—but only once in it, and Jones kept him busy in the ring. He also kept him undefeated. "Mike has been like a father to me," Costello says. "He really took care of me. He gave me anything I wanted. I didn't have to work. No hassles." By the beginning of 1983, Jones was pursuing Don King, the promoter, for a shot against champion Leroy Haley. Costello was ready—"He had become a boxer-puncher," Valle says—but King wasn't listening.
"I knew I would get a title shot but didn't know when," Costello says. In May of 1983 Haley lost the crown to Curry, a hard-used fighter who had suffered through his share of wars, and Jones intensified his pressure on King. He chased King all over the country, finally cornering him in Las Vegas in July of '83, on the eve of the Mustafa Hamsho-Wilfred Benitez fight. King didn't show for a meeting he'd set with Jones in Vegas. So Jones went to King's room in the Dunes Hotel and knocked on the door. King asked who was there.
"Room service!" said Mike, disguising his voice.
King opened the door and rolled his eyes. "Jonesy! What do you want?"
"You know what I want," said Jones.
It was at that meeting that King promised Costello a title shot early in 1984.
"I was a little worried because the fight was in Curry's home state [ Texas]," Costello says. "But after the first round I saw he had only one style, and that was coming in. He was tough. He could take a punch. But I started laying it on him. I knew sooner or later I was going to catch him, and sure enough I did."
The kid from Kingston was champion of the world. Then he whipped Shields in a fight that many thought he would lose, and that led to Mamby, who took the fight on five days' notice after Haley backed out, supposedly with a hand injury. Mamby used all the tricks he'd picked up over the years—the cut on Costello's eyelid was the result of a butt—but Costello was simply too much for him. Mamby ended up hanging in there on pride alone, with two cuts on his face and a mouthful of blood. At best, he won only two rounds, the first and the last.