British light heavyweight Joshua Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a competitive 10-round fight at the Manchester venue.
But Parker had his moments, connecting with powerful clean blows in a fight where the styles never quite clicked, with constant grabbing disrupting the contest.
The officials scored it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my finest display but how do champions respond? They win," Buatsi commented in the ringside as he was greeted with boos from the crowd.
The Londoner got back to winning after his maiden career setback - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Various analysts believed the challenger, thirty-one, merited the decision but the Derbyshire fighter endured the second setback of his 28-bout professional journey.
Buatsi Claims Triumph in Dull Encounter
The fighter's advancement has stalled in recent years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now stands trying to realize his potential - perhaps in what seems like a last chance - under fresh management.
He opened tentatively, with neither fighter ready to take risks in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second bout at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for the favorite, who utilized a protective stance to narrowly win the more effective rounds.
The spectators' acceptance wore thin amid regular grabbing, with Parker going down various instances during close exchanges.
The underdog ended stronger, but many rounds were hard to judge. Although, ex-champion the boxing analyst - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just one round.
Buatsi progresses, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a excellent Manchester vs Manchester battle to capture the continental title.
The venue grew hushed for a deeply poignant memorial before the fight as ten bells rang in remembrance of Manchester's own Hatton, who passed away aged 46 in last month.
It was the premier televised fight night in the urban center since Hatton's passing. As the final chime faded, the quiet became a shout of "there's just one Ricky Hatton".
The action within the ring matched the feeling. Arthur was sent to the canvas by a left hook directly to the jaw in the second round, standing uncertainly to his footing on the referee's count.
But the traditional red attire of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was marked up soon, significant bruising forming under his face as the duo exchanged powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity seldom decreased over the full distance.
Arthur edged the decision with official scores of even score, 115-113 and wider gap, but each competitor were determined and brave, exactly what their hero Hatton represented.
