British light-heavyweight Joshua Buatsi secured a victory yet underwhelming debut to his career under recent management with a points victory over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a majority decision in a competitive 10-round fight at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a match where the techniques didn't complement each other, with excessive holding marring the contest.
The officials had it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my best showing but how do champions respond? They prevail," the victor stated in the ringside as he was greeted with negative reactions from the spectators.
The British fighter got back to winning after his maiden career setback - an thrilling contest with his previous opponent in February - to earn a 20th career victory.
Various analysts thought the challenger, 31, deserved the decision but the British boxer experienced the second defeat of his 28-fight professional journey.
The Champion Claims Win in Slow Match
The fighter's advancement has plateaued in recent years through management issues and extended periods of inactivity.
Previously predicted as the future of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second fight at the higher weight class.
By the halfway stage, the underdog had stayed in contention, causing problems for the favorite, who operated with a tight guard to barely take the better periods.
The audience's tolerance wore thin during frequent holding, with the challenger going down multiple occasions during clinches.
The underdog closed well, but many rounds were challenging to assess. Although, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the likes of heavy hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Homage Motivates Manchester Derby Contest
In the secondary fight, Arthur beat Bradley Rea by split-decision in a terrific all-Manchester contest to capture the European light heavyweight belt.
The arena fell silent for a deeply poignant tribute before the fight as a bell ceremony tolled in remembrance of the city's native Hatton, who succumbed 46 years old in September.
It was the premier televised fight night in the location since the passing of Hatton. As the concluding sound faded, the stillness became a roar of "there's only one Ricky Hatton".
The fighting within the ring reflected the sentiment. The eventual winner was floored by a significant blow flush on the jaw in the early round, standing uncertainly to his position on the count of eight.
But the traditional red attire of Arthur soon pressed ahead again. On the opposite side, Rea - in opposing blue - was injured early, significant bruising developing under his orbital area as the pair landed punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
Arthur barely secured the result with scoring tallies of even score, 115-113 and 115-112, but both fighters were determined and brave, all the qualities their idol the legend represented.
