UK light heavyweight Joshua Buatsi secured a victory yet disappointing debut to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a competitive 10-round contest at the boxing arena.
But Parker had his moments, connecting with powerful individual punches in a fight where the techniques never quite clicked, with excessive holding spoiling the contest.
The officials scored it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest showing but what defines champions? They succeed," Buatsi stated in the ringside as he was greeted with disapproval from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with his previous opponent in February - to secure a 20th pro success.
Various analysts believed Parker, 31, merited the decision but the contender experienced the second setback of his 28-fight professional journey.
The Champion Secures Triumph in Slow Encounter
The fighter's advancement has stalled in recent times through management issues and considerable time of lack of fights.
Previously predicted as the future of UK boxing, he now is positioned trying to realize his potential - maybe in what appears to be a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter willing to be aggressive in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after damaging his hand during the bout, was making just his second appearance at the higher weight class.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who utilized a protective stance to narrowly win the cleaner rounds.
The audience's tolerance wore thin amid regular grabbing, with the challenger going down multiple occasions during grappling.
The underdog ended stronger, but many rounds were difficult to score. Nevertheless, ex-champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires Local Rivalry Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent local rivalry battle to win the continental championship.
The arena grew hushed for a profoundly moving tribute before the fight as ten bells sounded in remembrance of Manchester's own Ricky Hatton, who passed away 46 years old in recently.
It was the premier televised fight night in the location since Hatton's death. As the last bell faded, the silence gave way to a chant of "there's only one Ricky Hatton".
The action inside the ropes reflected the feeling. Arthur was floored by a significant blow squarely on the jaw in the early round, getting up unsteadily to his position on the eight count.
But the red-colored attire of Arthur soon came forward again. On the opposite side, the opponent - in opposing blue - was damaged early, noticeable damage developing under his face as the duo landed punishing blows.
Rea, 27, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action rarely dropped over 12 rounds.
The victor edged the result with judges scorecards of even score, close margin and clearer margin, but the two athletes were relentless and courageous, everything their idol Hatton stood for.
