British light-heavyweight Joshua Buatsi made a winning yet disappointing start to his career under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a tight ten-round contest at the boxing arena.
But the challenger found success, delivering effective single shots in a match where the styles failed to mesh, with frequent clinching spoiling the action.
The officials had it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi commented in the arena as he was faced negative reactions from the crowd.
The Londoner got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to claim a 20th pro success.
Various analysts believed Parker, thirty-one, merited the decision but the contender experienced the second loss of his 28-match career.
The Champion Earns Win in Slow Encounter
Buatsi's progress has plateaued in the past few years through management issues and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to realize his potential - possibly in what seems like a final roll of the dice - under recent support.
He started carefully, with both competitors ready to be aggressive in a cagey early stages.
The challenger, whose sole prior loss 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 fight's midpoint, the underdog had kept it close, making life awkward for the favorite, who worked behind a solid defense to narrowly win the cleaner periods.
The spectators' acceptance diminished during regular grabbing, with Parker slipping to the canvas multiple occasions during clinches.
Parker ended stronger, but multiple periods were hard to judge. Although, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, awarding Buatsi just one round.
The victor moves on, but with the likes of heavy hitter David Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Hatton Memorial Inspires Local Rivalry Battle
In the co-main event, Arthur beat Rea by divided decision in a outstanding all-Manchester contest to win the European light heavyweight title.
The arena fell silent for a extremely emotional memorial ahead of the contest as ten bells tolled in remembrance of Manchester's own Hatton, who passed away at age 46 in recently.
It was the premier televised match card in the city since the passing of Hatton. As the last bell faded, the silence transitioned to a roar of "only one Ricky Hatton".
The competition inside the ropes matched the sentiment. Arthur was sent to the canvas by a significant blow squarely on the jaw in the second round, getting up unsteadily to his footing on the eight count.
But the Manchester United-red shorts of Arthur soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged quickly, noticeable damage appearing under his eye as the duo exchanged hard punches.
The challenger, 27, landed power punches but the champion, 34, responded in kind with effective uppercuts as the pace rarely dropped over 12 rounds.
The victor barely secured the decision with judges scorecards of draw, narrow lead and wider gap, but the two athletes were persistent and courageous, everything their inspiration Hatton represented.
