British light-heavyweight Joshua Buatsi secured a victory yet unimpressive debut to life under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a competitive 10-round fight at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a match where the styles never quite clicked, with constant grabbing spoiling the action.
The scoring judges judged it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my best display but how do champions respond? They prevail," Buatsi commented in the ringside as he was met by disapproval from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to earn a 20th career victory.
Some ringside observers thought the challenger, thirty-one, deserved the victory but the Derbyshire fighter suffered the second defeat of his 28-bout career.
The Champion Claims Win in Dull Encounter
The fighter's advancement has plateaued in recent years through management issues and considerable time of inactivity.
Once tipped as the next star of British boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a last chance - under fresh management.
He opened tentatively, with both competitors prepared to be aggressive in a tentative opening few rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who utilized a protective stance to barely take the more effective rounds.
The spectators' acceptance diminished amid constant clinching, with Parker going down multiple occasions during grappling.
Parker closed well, but many rounds were hard to judge. However, former world champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, scoring for Buatsi just a single round.
The victor advances, but with the presence of heavy hitter Benavidez, and Russian star Bivol leading the category, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Contest
In the secondary fight, Arthur defeated Rea by split-decision in a excellent local rivalry battle to win the European light heavyweight title.
The venue grew hushed for a profoundly moving memorial prior to the bout as 10 bells tolled in remembrance of local hero Hatton, who passed away 46 years old in September.
It was the premier televised fight night in the location since the passing of Hatton. As the final chime ended, the stillness transitioned to a shout of "there's just one Hatton".
The fighting during the bout equaled the emotion. Arthur was sent to the canvas by a left hook flush on the jaw in the initial stage, getting up unsteadily to his feet on the count of eight.
But the Manchester United-red shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in competitive blue - was marked up quickly, heavy swelling appearing under his face as the pair traded punishing blows.
The challenger, 27, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the pace seldom decreased over the full distance.
Arthur barely secured the decision with judges scorecards of 114-114, narrow lead and 115-112, but each competitor were relentless and brave, exactly what their idol Hatton stood for.
