British light heavyweight Joshua Buatsi earned a win yet underwhelming beginning to his career under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a tight 10-round contest at the Manchester venue.
But Parker landed significant shots, landing some telling clean blows in a contest where the approaches never quite clicked, with constant grabbing spoiling the contest.
The officials had it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They succeed," Buatsi stated in the ring as he was faced boos from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with Callum Smith in last winter - to claim a twentieth professional win.
Several boxing experts believed the challenger, 31, deserved the decision but the Derbyshire fighter endured the second loss of his 28-fight career.
Buatsi Earns Win in Slow Affair
The fighter's advancement has stalled in recent years through management issues and considerable time of inactivity.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He began cautiously, with neither fighter ready to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was making just his second fight at light heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for Buatsi, who worked behind a protective stance to barely take the better periods.
The audience's tolerance wore thin during constant clinching, with Parker going down several times during clinches.
Parker ended stronger, but multiple periods were challenging to assess. Although, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the likes of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Inspires Local Rivalry Fight
In the co-main event, Arthur beat Rea by split-decision in a excellent local rivalry contest to secure the continental championship.
The stadium fell silent for a extremely emotional memorial prior to the bout as ten bells tolled in remembrance of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the last bell faded, the stillness transitioned to a roar of "only one Ricky Hatton".
The action during the bout matched the emotion. Arthur was floored by a powerful punch directly to the jaw in the early round, standing uncertainly to his footing on the referee's count.
But the traditional red equipment of Arthur soon advanced again. From the other corner, Rea - in rival City blue - was marked up soon, heavy swelling developing under his orbital area as the fighters landed powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, 34, responded in kind with effective uppercuts as the intensity rarely dropped over 12 rounds.
Arthur edged the decision with scoring tallies of even score, close margin and wider gap, but both fighters were persistent and brave, all the qualities their hero Hatton embodied.
