UK light heavyweight Joshua Buatsi earned a win yet disappointing beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a majority decision in a competitive 10-round fight at the Co-op Live Arena.
But Parker landed significant shots, landing some telling clean blows in a contest where the styles failed to mesh, with constant grabbing disrupting the action.
Two judges had it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what defines champions? They prevail," Buatsi said in the arena as he was faced disapproval from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in February - to claim a 20th career victory.
Several boxing experts thought the challenger, 31, merited the decision but the contender experienced the second loss of his 28-match career.
Buatsi Earns Triumph in Slow Affair
The fighter's advancement has stalled in the past few years through promotional disputes and long spells of lack of fights.
Previously predicted as the next star of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors willing to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was participating in his second bout at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a tight guard to edge the better periods.
The audience's tolerance diminished amid regular grabbing, with Parker falling to the floor several times during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. Although, former world champion Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Arthur overcame Rea by close verdict in a outstanding local rivalry contest to win the continental championship.
The arena became quiet for a deeply poignant homage prior to the bout as a bell ceremony sounded in honor of local hero Ricky Hatton, who passed away aged 46 in September.
It was the first major televised fight night in the city since Hatton's death. As the last bell disappeared, the silence became a shout of "only one Hatton".
The fighting during the bout matched the emotion. The eventual winner was floored by a powerful punch flush on the chin in the initial stage, standing uncertainly to his footing on the referee's count.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, Rea - in rival City blue - was damaged early, heavy swelling forming under his face as the fighters landed powerful shots.
The challenger, 27, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the pace seldom decreased over the full distance.
Arthur narrowly won the decision with official scores of draw, narrow lead and clearer margin, but each competitor were persistent and brave, exactly what their inspiration Hatton stood for.
