British light-heavyweight Joshua Buatsi made a winning yet underwhelming debut to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a competitive ten-round contest at the Manchester venue.
But the challenger had his moments, landing some telling single shots in a contest where the styles failed to mesh, with excessive holding marring the action.
The officials judged it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my finest performance but what defines champions? They prevail," the victor said in the ringside as he was met by boos from the spectators.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts thought Parker, thirty-one, deserved the victory but the Derbyshire fighter endured the second defeat of his 28-bout career.
The Champion Earns Victory in Uneventful Match
The fighter's advancement has slowed in recent times through management issues and extended periods of lack of fights.
Previously predicted as the next star of the British fight scene, he now is positioned trying to achieve expectations - perhaps in what appears to be a ultimate opportunity - under recent support.
He started carefully, with neither fighter ready to overcommit in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was competing in only his second bout at the higher weight class.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who operated with a tight guard to edge the cleaner periods.
The spectators' acceptance diminished amid frequent holding, with the challenger going down multiple occasions during grappling.
Parker ended stronger, but multiple periods were challenging to assess. However, previous titleholder the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Tribute Inspires Manchester Derby Battle
In the secondary fight, Arthur beat Rea by close verdict in a outstanding Manchester vs Manchester fight to secure the European light heavyweight championship.
The venue became quiet for a extremely emotional tribute prior to the bout as ten bells rang in honor of the city's native Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the last bell disappeared, the quiet gave way to a roar of "there's only one Ricky Hatton".
The action inside the ropes equaled the feeling. The eventual winner was floored by a significant blow squarely on the jaw in the early round, rising shakily to his position on the referee's count.
But the traditional red equipment of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was injured quickly, noticeable damage developing under his face as the pair landed punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur barely secured the verdict with official scores of even score, 115-113 and clearer margin, but each competitor were determined and courageous, everything their inspiration the legend represented.
