UK light-heavyweight Joshua Buatsi made a winning yet disappointing beginning to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a tight 10-round bout at the boxing arena.
But Parker had his moments, connecting with powerful single shots in a fight where the approaches didn't complement each other, with constant grabbing spoiling the fight.
The officials scored it 96-94 for to the winner, with the remaining official a even score.
"It wasn't my best showing but what do champions do? They win," Buatsi commented in the arena as he was met by negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Various analysts believed the challenger, 31, should have been awarded the decision but the contender experienced the second loss of his 28-fight professional journey.
The Champion Earns Triumph in Dull Affair
Buatsi's progress has stalled in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what seems like a ultimate opportunity - under recent support.
He started carefully, with both competitors ready to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at the higher weight class.
By the middle rounds, Parker had kept it close, making life awkward for the favorite, who utilized a solid defense to edge the better stanzas.
The crowd's patience decreased because of regular grabbing, with Parker falling to the floor multiple occasions during grappling.
Parker closed well, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the presence of hard hitter David Benavidez, and Russian star Bivol leading the category, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the supporting bout, Arthur beat Rea by split-decision in a excellent Manchester vs Manchester battle to capture the continental title.
The arena grew hushed for a profoundly moving homage before the fight as ten bells sounded in honor of the city's native Hatton, who died 46 years old in last month.
It was the premier televised boxing event in the location since Hatton's death. As the last bell faded, the stillness gave way to a roar of "only one Ricky Hatton".
The fighting during the bout matched the sentiment. Arthur was floored by a left hook directly to the face in the second round, getting up unsteadily to his feet on the eight count.
But the traditional red shorts of the fighter soon came forward again. Across the ring, Rea - in opposing blue - was marked up early, significant bruising developing under his face as the pair exchanged hard punches.
The challenger, twenty-seven, landed power punches but the champion, 34, fought fire with fire with powerful upward punches as the pace seldom decreased over twelve rounds.
The victor edged the decision with scoring tallies of draw, close margin and clearer margin, but the two athletes were determined and brave, everything their inspiration the legend embodied.
