UK light heavyweight Joshua Buatsi secured a victory yet underwhelming debut to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a tight 10-round fight at the Co-op Live Arena.
But Parker had his moments, delivering effective clean blows in a fight where the techniques never quite clicked, with frequent clinching disrupting the fight.
The scoring judges judged it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my finest showing but how do champions respond? They prevail," the victor said in the arena as he was faced boos from the audience.
The Londoner returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to secure a twentieth professional win.
Various analysts believed the challenger, 31, merited the victory but the Derbyshire fighter endured the second defeat of his 28-bout professional journey.
Buatsi Earns Victory in Uneventful Affair
His career development has plateaued in recent times through promotional disputes and long spells of lack of fights.
Previously predicted as the future of UK boxing, he now stands trying to fulfil that early promise - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers prepared to take risks in a tentative early stages.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was making just his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who worked behind a protective stance to edge the more effective rounds.
The crowd's patience diminished during regular grabbing, with the challenger going down multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, former world champion Carl Frampton - providing analysis for Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the likes of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still seems difficult.
Hatton Tribute Inspires Local Rivalry Contest
In the secondary fight, Arthur overcame Rea by divided decision in a outstanding all-Manchester contest to win the European light heavyweight title.
The stadium fell silent for a extremely emotional memorial before the fight as 10 bells tolled in memory of Manchester's own Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the last bell faded, the quiet transitioned to a chant of "there's only one Hatton".
The fighting inside the ropes matched the feeling. The eventual winner was sent to the canvas by a significant blow flush on the face in the second round, rising shakily to his position on the referee's count.
But the red-colored attire of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was marked up soon, significant bruising appearing under his face as the duo exchanged powerful shots.
Rea, 27, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the action seldom decreased over the full distance.
The victor narrowly won the decision with scoring tallies of even score, 115-113 and clearer margin, but the two athletes were relentless and courageous, all the qualities their hero the legend represented.
