British light heavyweight Joshua Buatsi secured a victory yet disappointing debut to life under fresh promotional backing with a decision win over Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a majority decision in a competitive 10-round bout at the Manchester venue.
But the challenger had his moments, delivering effective individual punches in a contest where the approaches never quite clicked, with constant grabbing disrupting the fight.
The officials had it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my best display but how do champions respond? They prevail," Buatsi stated in the arena as he was faced negative reactions from the spectators.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in February - to claim a 20th career victory.
Several boxing experts believed Parker, 31, merited the decision but the British boxer endured the second loss of his 28-fight professional journey.
The Champion Earns Triumph in Slow Match
His career development has stalled in recent times through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of the British fight scene, he now stands trying to realize his potential - perhaps in what feels like a last chance - under fresh management.
He began cautiously, with both competitors prepared to be aggressive in a cagey opening few rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second appearance at the higher weight class.
By the fight's midpoint, Parker had kept it close, creating difficulties for the favorite, who worked behind a tight guard to narrowly win the better periods.
The spectators' acceptance diminished during regular grabbing, with the challenger going down multiple occasions during clinches.
Parker closed well, but multiple periods were challenging to assess. However, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Fight
In the co-main event, Arthur beat Bradley Rea by divided decision in a excellent local rivalry contest to win the continental championship.
The stadium grew hushed for a deeply poignant memorial ahead of the contest as ten bells sounded in remembrance of Manchester's own Hatton, who passed away 46 years old in last month.
It was the premier televised boxing event in the location since the passing of Hatton. As the last bell faded, the silence transitioned to a shout of "there's just one Hatton".
The action inside the ropes equaled the sentiment. Arthur was sent to the canvas by a left hook flush on the chin in the early round, getting up unsteadily to his feet on the referee's count.
But the red-colored shorts of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was damaged soon, heavy swelling appearing under his orbital area as the pair exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the intensity hardly diminished over the full distance.
The victor edged the decision with official scores of 114-114, 115-113 and clearer margin, but both fighters were determined and courageous, all the qualities their hero the legend embodied.
