UK light-heavyweight Joshua Buatsi secured a victory yet underwhelming beginning 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 judges' verdict in a close 10-round contest at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling single shots in a contest where the techniques failed to mesh, with excessive holding disrupting the contest.
The officials had it 96-94 for to the winner, with the remaining official a even score.
"It wasn't my greatest display but how do champions respond? They succeed," Buatsi commented in the arena as he was greeted with disapproval from the crowd.
The British fighter got back to winning after his first professional defeat - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Several boxing experts felt the challenger, 31, merited the victory but the British boxer experienced the second defeat of his 28-fight professional journey.
Buatsi Earns Win in Dull Affair
Buatsi's progress has slowed in recent times through contract problems and long spells of lack of fights.
Once tipped as the rising talent of British boxing, he now stands trying to achieve expectations - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with the two boxers ready to take risks in a tentative early stages.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after breaking his hand in the contest, was competing in only his second fight at the higher weight class.
By the halfway stage, Parker had made it competitive, making life awkward for the favorite, who utilized a solid defense to barely take the cleaner periods.
The crowd's patience wore thin amid frequent holding, with Parker falling to the floor multiple occasions during grappling.
Parker closed well, but many rounds were difficult to score. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
The victor advances, but with the caliber of hard hitter Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the secondary fight, Lyndon Arthur beat Bradley Rea by split-decision in a terrific Manchester vs Manchester battle to win the continental belt.
The venue grew hushed for a extremely emotional homage prior to the bout as a bell ceremony sounded in honor of local hero Hatton, who died 46 years old in recently.
It was the first major televised boxing event in the location since the passing of Hatton. As the concluding sound disappeared, the silence gave way to a shout of "only one Hatton".
The competition inside the ropes equaled the feeling. Arthur was knocked down by a powerful punch directly to the face in the second round, getting up unsteadily to his footing on the count of eight.
But the traditional red equipment of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was marked up quickly, significant bruising appearing under his face as the fighters traded powerful shots.
The challenger, 27, landed power punches but the champion, thirty-four, responded in kind with stinging uppercuts as the pace rarely dropped over twelve rounds.
The victor narrowly won the verdict with official scores of even score, close margin and 115-112, but each competitor were persistent and courageous, all the qualities their inspiration Hatton stood for.
