UK light-heavyweight Joshua Buatsi secured a victory yet unimpressive beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a close 10-round fight at the Manchester venue.
But the challenger found success, delivering effective clean blows in a contest where the techniques failed to mesh, with excessive holding marring the contest.
Two judges had it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my finest performance but how do champions respond? They succeed," the victor said in the arena as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a 20th pro success.
Several boxing experts believed the challenger, thirty-one, should have been awarded the decision but the British boxer experienced the second setback of his 28-match career.
The Champion Secures Triumph in Uneventful Match
The fighter's advancement has slowed in recent times through promotional disputes and considerable time of lack of fights.
Once tipped as the next star of UK boxing, he now stands trying to achieve expectations - perhaps in what appears to be a final roll of the dice - under fresh management.
He started carefully, with both competitors ready to overcommit in a tentative initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second appearance at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for the favorite, who operated with a protective stance to narrowly win the cleaner stanzas.
The audience's tolerance diminished during frequent holding, with Parker slipping to the canvas various instances during clinches.
Parker finished the stronger, but several stanzas were difficult to score. Although, former world champion Carl Frampton - working with Dazn - had it particularly wide for Parker, scoring for Buatsi just a single round.
The victor advances, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Memorial Fuels Local Rivalry Fight
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a excellent local rivalry contest to win the European light-heavyweight belt.
The stadium became quiet for a extremely emotional homage before the fight as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who died 46 years old in recently.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the last bell ended, the stillness became a chant of "there's only one Hatton".
The fighting within the ring matched the feeling. Arthur was sent to the canvas by a significant blow directly to the face in the early round, standing uncertainly to his position on the referee's count.
But the traditional red attire of Arthur soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was injured early, significant bruising developing under his orbital area as the pair exchanged punishing blows.
Rea, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with powerful upward punches as the action seldom decreased over 12 rounds.
The victor narrowly won the decision with official scores of even score, narrow lead and wider gap, but both fighters were relentless and full of heart, everything their inspiration Hatton represented.
