British light-heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a tight ten-round bout at the Manchester venue.
But the challenger found success, connecting with powerful clean blows in a fight where the techniques didn't complement each other, with constant grabbing spoiling the contest.
The officials scored it 96-94 in favor to the winner, with the third a even score.
"It wasn't my greatest display but how do champions respond? They succeed," Buatsi stated in the arena as he was faced negative reactions from the spectators.
The British fighter bounced back after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a 20th pro success.
Some ringside observers felt the challenger, 31, merited the victory but the British boxer endured the second defeat of his 28-fight professional journey.
Buatsi Claims Victory in Slow Encounter
His career development has stalled in recent times through contract problems and long spells of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors ready to be aggressive in a tentative opening few rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second fight at light heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a solid defense to edge the cleaner periods.
The audience's tolerance diminished amid regular grabbing, with the challenger falling to the floor multiple occasions during grappling.
The underdog closed well, but many rounds were challenging to assess. However, former world champion the boxing analyst - working with the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor progresses, but with the caliber of power puncher Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Hatton Tribute Fuels Local Rivalry Battle
In the supporting bout, Lyndon Arthur beat Rea by divided decision in a outstanding Manchester vs Manchester contest to secure the European light-heavyweight championship.
The venue grew hushed for a deeply poignant memorial prior to the bout as 10 bells tolled in remembrance of local hero Ricky Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the concluding sound disappeared, the stillness became a shout of "there's just one Hatton".
The action inside the ropes equaled the feeling. Arthur was sent to the canvas by a left hook flush on the jaw in the initial stage, standing uncertainly to his position on the count of eight.
But the red-colored equipment of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up early, significant bruising appearing under his face as the pair exchanged powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor edged the result with scoring tallies of draw, close margin and wider gap, but both fighters were persistent and courageous, all the qualities their inspiration the legend embodied.
