UK light-heavyweight Joshua Buatsi earned a win yet underwhelming debut to his career under new promoters with a decision win over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a competitive 10-round fight at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a contest where the styles never quite clicked, with excessive holding disrupting the contest.
The officials scored it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest performance but how do champions respond? They prevail," the victor stated in the ringside as he was faced boos from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts believed the challenger, thirty-one, merited the victory but the Derbyshire fighter suffered the second defeat of his 28-match professional journey.
The Champion Earns Win in Slow Affair
Buatsi's progress has slowed in recent times through management issues and extended periods of lack of fights.
Once tipped as the future of British boxing, he now is positioned trying to achieve expectations - perhaps in what appears to be a ultimate opportunity - under fresh management.
He started carefully, with neither fighter prepared to overcommit in a calculated early stages.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who operated with a solid defense to narrowly win the better stanzas.
The audience's tolerance wore thin because of regular grabbing, with Parker slipping to the canvas multiple occasions during grappling.
Parker closed well, but multiple periods were challenging to assess. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Homage Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Rea by divided decision in a outstanding local rivalry battle to secure the European light-heavyweight title.
The venue became quiet for a extremely emotional memorial prior to the bout as ten bells rang in honor of the city's native Ricky Hatton, who died aged 46 in recently.
It was the first major televised boxing event in the city since Hatton's death. As the final chime faded, the silence transitioned to a shout of "there's only one Hatton".
The fighting during the bout equaled the emotion. Arthur was knocked down by a left hook directly to the jaw in the initial stage, standing uncertainly to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon pressed ahead again. Across the ring, the opponent - in rival City blue - was marked up early, significant bruising developing under his face as the fighters traded hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over twelve rounds.
The victor barely secured the result with official scores of even score, narrow lead and 115-112, but both fighters were relentless and brave, all the qualities their idol the legend represented.
