British light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a close ten-round fight at the Manchester venue.
But Parker found success, delivering effective individual punches in a match where the approaches didn't complement each other, with excessive holding spoiling the contest.
The scoring judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my best showing but what defines champions? They succeed," Buatsi said in the arena as he was greeted with negative reactions from the audience.
The British fighter bounced back after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Various analysts thought Parker, thirty-one, merited the win but the contender experienced the second loss of his 28-fight professional journey.
The Champion Claims Victory in Uneventful Encounter
The fighter's advancement has stalled in recent times through management issues and long spells of lack of fights.
Previously predicted as the next star of UK boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a last chance - under new promotional backing.
He started carefully, with neither fighter prepared to take risks in a cagey opening few rounds.
Parker, whose sole prior loss came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second fight at light-heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for the favorite, who operated with a solid defense to narrowly win the cleaner rounds.
The spectators' acceptance decreased during constant clinching, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog ended stronger, but multiple periods were challenging to assess. However, previous titleholder the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just one round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur defeated Rea by close verdict in a terrific Manchester vs Manchester fight to secure the European light heavyweight championship.
The venue fell silent for a extremely emotional tribute prior to the bout as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who succumbed at age 46 in last month.
It was the first major televised match card in the urban center since Hatton's death. As the concluding sound faded, the silence gave way to a chant of "there's only one Hatton".
The action within the ring equaled the sentiment. Arthur was knocked down by a powerful punch flush on the jaw in the early round, rising shakily to his position on the count of eight.
But the red-colored equipment of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was marked up early, heavy swelling developing under his face as the duo landed punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, responded in kind with powerful upward punches as the intensity seldom decreased over 12 rounds.
The victor barely secured the result with judges scorecards of draw, 115-113 and 115-112, but each competitor were determined and full of heart, all the qualities their hero the legend stood for.
