British light heavyweight Joshua Buatsi made a winning yet underwhelming debut to life under new promoters with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight ten-round contest at the Co-op Live Arena.
But Parker found success, connecting with powerful individual punches in a fight where the styles didn't complement each other, with excessive holding spoiling the fight.
Two judges had it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest performance but what do champions do? They prevail," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The British fighter returned to winning ways after his initial pro loss - an epic battle with his previous opponent in February - to claim a 20th career victory.
Some ringside observers felt Parker, thirty-one, merited the decision but the contender suffered the second defeat of his 28-bout career.
Buatsi Claims Triumph in Uneventful Encounter
His career development has slowed in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the future of British boxing, he now finds himself trying to realize his potential - perhaps in what seems like a ultimate opportunity - under recent support.
He started carefully, with both competitors ready to be aggressive in a tentative early stages.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second fight at light-heavyweight.
By the halfway stage, the underdog had kept it close, causing problems for Buatsi, who utilized a solid defense to narrowly win the cleaner stanzas.
The spectators' acceptance wore thin amid regular grabbing, with Parker slipping to the canvas multiple occasions during close exchanges.
The underdog finished the stronger, but multiple periods were challenging to assess. However, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor moves on, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Memorial Inspires Manchester Derby Fight
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a terrific all-Manchester battle to secure the European light-heavyweight championship.
The arena grew hushed for a deeply poignant memorial ahead of the contest as a bell ceremony sounded in honor of the city's native Ricky Hatton, who passed away 46 years old in September.
It was the initial significant broadcast match card in the urban center since the passing of Hatton. As the last bell ended, the silence transitioned to a roar of "there's just one Hatton".
The action during the bout reflected the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the face in the initial stage, getting up unsteadily to his feet on the count of eight.
But the Manchester United-red attire of the fighter soon pressed ahead again. From the other corner, the opponent - in competitive blue - was injured quickly, significant bruising forming under his face as the pair traded powerful shots.
Rea, 27, connected with strong blows but the champion, 34, matched the intensity with stinging uppercuts as the action rarely dropped over the full distance.
The victor narrowly won the verdict with scoring tallies of draw, narrow lead and 115-112, but both fighters were determined and full of heart, everything their hero the legend embodied.
