UK light-heavyweight Joshua Buatsi earned a win yet underwhelming start to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a competitive 10-round bout at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful single shots in a contest where the techniques didn't complement each other, with excessive holding marring the fight.
The officials had it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest performance but how do champions respond? They win," Buatsi commented in the ringside as he was met by boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Various analysts believed the challenger, thirty-one, deserved the decision but the contender suffered the second setback of his 28-bout career.
Buatsi Earns Triumph in Dull Match
The fighter's advancement has plateaued in recent years through management issues and long spells of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a ultimate opportunity - under recent support.
He started carefully, with both competitors prepared to overcommit in a cagey initial rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after breaking his hand in the contest, was participating in his second appearance at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a solid defense to narrowly win the better stanzas.
The audience's tolerance diminished because of constant clinching, with Parker slipping to the canvas various instances during grappling.
The underdog ended stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the caliber of hard hitter David Benavidez, and Russian star Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Tribute Inspires Manchester Derby Contest
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a outstanding local rivalry contest to secure the European light-heavyweight belt.
The stadium became quiet for a deeply poignant memorial prior to the bout as ten bells rang in memory of local hero Hatton, who died 46 years old in September.
It was the first major televised match card in the urban center since Hatton's passing. As the final chime ended, the silence became a roar of "only one Hatton".
The competition within the ring equaled the emotion. Arthur was floored by a significant blow flush on the face in the initial stage, standing uncertainly to his feet on the count of eight.
But the traditional red shorts of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was marked up early, noticeable damage developing under his eye as the fighters traded hard punches.
Rea, 27, connected with strong blows but the champion, 34, responded in kind with effective uppercuts as the intensity seldom decreased over the full distance.
The victor narrowly won the result with scoring tallies of 114-114, narrow lead and 115-112, but both fighters were relentless and courageous, all the qualities their inspiration the legend embodied.
