UK light-heavyweight Joshua Buatsi made a winning yet disappointing beginning to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a competitive 10-round fight at the Manchester venue.
But the challenger found success, landing some telling individual punches in a fight where the approaches failed to mesh, with constant grabbing spoiling the contest.
Two judges had it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but how do champions respond? They prevail," Buatsi commented in the ring as he was met by boos from the crowd.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in last winter - to secure a twentieth professional win.
Various analysts thought the challenger, 31, merited the victory but the British boxer experienced the second loss of his 28-match professional journey.
The Champion Earns Win in Dull Match
Buatsi's progress has plateaued in the past few years through contract problems and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now stands trying to achieve expectations - maybe in what appears to be a last chance - under new promotional backing.
He opened tentatively, with neither fighter willing to overcommit in a tentative early stages.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after damaging his hand mid-fight, was competing in only his second appearance at light heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who utilized a tight guard to barely take the cleaner stanzas.
The audience's tolerance diminished during frequent holding, with the challenger going down various instances during clinches.
The underdog ended stronger, but multiple periods were challenging to assess. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just a single round.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Tribute Fuels Manchester Derby Contest
In the secondary fight, Arthur defeated Bradley Rea by close verdict in a excellent local rivalry contest to secure the European light heavyweight title.
The stadium grew hushed for a deeply poignant memorial before the fight as a bell ceremony tolled in honor of Manchester's own Hatton, who passed away aged 46 in last month.
It was the first major televised boxing event in the location since Hatton's passing. As the final chime ended, the silence transitioned to a roar of "there's just one Hatton".
The action within the ring reflected the feeling. Arthur was floored by a significant blow directly to the jaw in the initial stage, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red equipment of Arthur soon came forward again. From the other corner, Rea - in opposing blue - was damaged early, significant bruising developing under his face as the pair exchanged punishing blows.
Rea, twenty-seven, landed power punches but the champion, 34, fought fire with fire with effective uppercuts as the action rarely dropped over 12 rounds.
The victor barely secured the result with official scores of draw, close margin and 115-112, but both fighters were determined and full of heart, everything their inspiration Hatton represented.
