UK light-heavyweight Joshua Buatsi secured a victory yet disappointing beginning to his career under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a close ten-round fight at the Manchester venue.
But Parker found success, delivering effective individual punches in a contest where the techniques failed to mesh, with excessive holding spoiling the fight.
The officials judged it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my finest performance but what defines champions? They win," the victor stated in the ring as he was greeted with boos from the crowd.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Several boxing experts thought Parker, thirty-one, should have been awarded the victory but the British boxer endured the second setback of his 28-match professional journey.
Buatsi Secures Victory in Uneventful Match
The fighter's advancement has slowed in recent times through contract problems and considerable time of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a last chance - under recent support.
He opened tentatively, with both competitors prepared to overcommit in a calculated early stages.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was making just his second fight at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for the favorite, who operated with a protective stance to edge the better rounds.
The spectators' acceptance wore thin during frequent holding, with Parker falling to the floor several times during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, ex-champion the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Hatton Homage Fuels Manchester Derby Battle
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent all-Manchester battle to win the European light heavyweight championship.
The arena became quiet for a extremely emotional homage prior to the bout as a bell ceremony rang in honor of Manchester's own Ricky Hatton, who passed away at age 46 in September.
It was the premier televised fight night in the location since the passing of Hatton. As the final chime ended, the quiet became a chant of "only one Hatton".
The fighting within the ring matched the feeling. Arthur was floored by a significant blow directly to the face in the early round, getting up unsteadily to his position on the count of eight.
But the red-colored shorts of Arthur soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged early, significant bruising forming under his orbital area as the pair exchanged powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over 12 rounds.
The victor narrowly won the verdict with scoring tallies of 114-114, 115-113 and clearer margin, but the two athletes were determined and brave, exactly what their inspiration Hatton represented.
