Carl Frampton prepares for defense of his featherweight title in his Las Vegas debut

More than 30 years ago in an outdoor ring at Caesars Palace, Irishman Barry McGuigan felt himself overcome by the 120-degree heat and his game featherweight-title challenger Steve Cruz.

“Say a prayer for me,” McGuigan told his cornermen after 12 rounds of the 1986 fight that still had three rounds remaining.

A disputed 15th-round knockdown of McGuigan allowed Cruz to take the belt by one point on two judges’ scorecards.

McGuigan, now a fight promoter, finds himself across the Strip at MGM Grand with his top fighter, Northern Ireland’s unbeaten Carl Frampton, defending the same World Boxing Assn. featherweight belt McGuigan lost all those years ago.

Frampton (23-0, 14 knockouts) meets Los Angeles’ former three-division world champion Leo Santa Cruz (32-1-1, 18 KOs) on Saturday night on Showtime.

“Of course there’s unfinished business,” McGuigan said. “Carl’s got to win this fight. I get a bit tense near the fights because success puts pressure on you — unbelievable pressure. I’m glad it’s him fighting, not me, because he loves pressure.”

McGuigan on Thursday recounted how deeply his bond with Frampton has grown since he first saw the then-amateur fight in the 2007 European Boxing Union Championships.

“In the final card, he lost,” McGuigan said, admitting the outcome deflected the attention Frampton deserved from boxing scouts. “They didn’t know, thanks be to God, but I looked at this guy and went, ‘Oh, my God!’

“He has reminded me of me since the moment I met him. Not stylistically. Fighting-wise, he’s definitely different. Not physiologically. Intellectually, he’s similar. But when I looked at him, when I met him the very moment at that national stadium … I knew he was just like me.”

McGuigan urged a friend to pull Frampton from his post-fight shower, and the former champion’s praise affected Frampton and his club coach, who disdained pro boxing.

“I’m going to look after this kid, and if anyone can look after him, I can,” McGuigan told Frampton’s amateur coach. “I know every nook and cranny in Northern Ireland. This kid’s like me, exactly like me, and I can take him through.”

McGuigan’s enthusiasm for Frampton wasn’t shared by everyone. He had an average showing against Wales’ Robbie Turley two years into his pro career and veteran English promoter Frank Warren said to McGuigan, “If this is the best prospect in Ireland.…”

McGuigan aligned Frampton with his son, Shane McGuigan, as trainer, and vowed, “Right, we’ll reinforce our determination to get where we’ll get and win the world title.”

By 2014, Frampton was a world super-bantamweight champion and he started a campaign to build his worldwide profile by fighting in the U.S. in 2015, boosting that plan with an action-filled fight against Santa Cruz in July.

Frampton won a majority decision by knocking then-unbeaten Santa Cruz to the ropes in the second round and landing the more convincing blows to seal his fighter-of-the-year performance.

“In the next two or three years, he’ll be involved in super-fights and he’s going to make a fortune,” McGuigan said of Frampton.

First, there’s the task of Saturday’s rematch in a fight considered a pick-’em at the betting window.

“I’m going to get the win,” Frampton said. “I feel like I’m stronger, punching harder. I’ll go into the trenches and dig it out. I have the psychological edge. I’ve beat him. I’ve hurt him. I want to prove all these awards I’ve picked up are justified.”

Frampton, 29, perhaps isn’t old enough yet to understand the magnitude of McGuigan’s sentimental Las Vegas return.

“We’re different men. Barry did his thing. He was a great champion. I’ve done my work. We’re obviously a great team, but it’s not all about carrying on what Barry’s done,” Frampton said.

Yet McGuigan, who lived in Belfast during his boxing career, several times fought tears as he discussed how their relationship has healed some old wounds. For McGuigan, their relationship has come to embody Northern Ireland’s own progression from the deadly “Troubles” that soaked the streets with the blood of fighting Protestants and Catholics.

McGuigan, a Catholic, is married to a Protestant, and the Protestant fighter he loves as a son is married to a Catholic.

In an interview with Showtime’s Mark Kriegel recently, Frampton said he’d learned McGuigan has a pre-fight tradition of visiting nuns who’ve taken a vow of silence in Ireland, asking them to pray for Frampton before each of his bouts.

“We want to be beacons of hope for people, because even though … there’s been peace [in Belfast] for 17 years, you scratch the surface and there’s still a lot of tension, bitterness and hatred,” McGuigan told The Times. “We want to stop that, and we want to do what we can.”

lance.pugmire@latimes.com

Twitter: @latimespugmire