British light-heavyweight Joshua Buatsi earned a win yet underwhelming start to his career under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a competitive ten-round fight at the Manchester venue.
But Parker had his moments, delivering effective clean blows in a fight where the techniques failed to mesh, with excessive holding disrupting the fight.
The scoring judges judged it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest display but how do champions respond? They succeed," the victor stated in the arena as he was faced disapproval from the crowd.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Some ringside observers felt the challenger, thirty-one, deserved the decision but the Derbyshire fighter endured the second setback of his 28-fight career.
Buatsi Secures Triumph in Uneventful Match
Buatsi's progress has plateaued in recent years through contract problems and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with the two boxers willing to take risks in a tentative opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for Buatsi, who utilized a solid defense to barely take the cleaner stanzas.
The audience's tolerance diminished during frequent holding, with the challenger going down various instances during grappling.
The underdog closed well, but several stanzas were hard to judge. Although, previous titleholder Carl Frampton - working with the broadcast network - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
Buatsi moves on, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Memorial Motivates Local Rivalry Contest
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a terrific Manchester vs Manchester battle to win the European light-heavyweight title.
The arena grew hushed for a deeply poignant tribute prior to the bout as 10 bells tolled in remembrance of the city's native Hatton, who succumbed at age 46 in recently.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound faded, the stillness gave way to a roar of "there's only one Hatton".
The competition within the ring reflected the sentiment. The eventual winner was sent to the canvas by a left hook directly to the face in the second round, standing uncertainly to his position on the count of eight.
But the red-colored shorts of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was damaged soon, heavy swelling forming under his face as the duo landed hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over twelve rounds.
Arthur barely secured the verdict with judges scorecards of 114-114, close margin and wider gap, but each competitor were persistent and brave, exactly what their inspiration the legend embodied.
