British light heavyweight Joshua Buatsi made a winning yet unimpressive start to his career under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a split decision in a tight 10-round contest at the Manchester venue.
But Parker found success, delivering effective individual punches in a fight where the techniques failed to mesh, with frequent clinching marring the contest.
Two judges scored it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest display but how do champions respond? They prevail," the victor stated in the ringside as he was met by boos from the audience.
The Londoner got back to winning after his first professional defeat - an thrilling contest with Callum Smith in last winter - to claim a twentieth professional win.
Several boxing experts felt the challenger, 31, deserved the decision but the contender experienced the second loss of his 28-match career.
Buatsi Earns Victory in Uneventful Encounter
The fighter's advancement has stalled in recent times through management issues and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to realize his potential - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with neither fighter ready to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against his former opponent in two years ago after breaking his hand in the contest, was making just his second bout at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who utilized a protective stance to barely take the better stanzas.
The audience's tolerance decreased during constant clinching, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but many rounds were difficult to score. However, former world champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, giving Buatsi just a single round.
Buatsi advances, but with the caliber of hard hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Homage Motivates All-Manchester Fight
In the co-main event, Arthur overcame Rea by close verdict in a excellent Manchester vs Manchester battle to secure the European light heavyweight belt.
The arena fell silent for a profoundly moving tribute prior to the bout as a bell ceremony sounded in memory of local hero Hatton, who succumbed aged 46 in September.
It was the premier televised fight night in the location since the passing of Hatton. As the concluding sound ended, the stillness gave way to a chant of "there's just one Hatton".
The fighting inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a left hook directly to the face in the early round, standing uncertainly to his footing on the referee's count.
But the traditional red attire of Arthur soon came forward again. From the other corner, the opponent - in opposing blue - was damaged soon, noticeable damage appearing under his eye as the fighters landed punishing blows.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the action hardly diminished over twelve rounds.
Arthur edged the result with scoring tallies of draw, close margin and 115-112, but each competitor were persistent and brave, all the qualities their idol Hatton represented.
