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 activity level appeared to earn him a judges' verdict in a tight 10-round fight at the Co-op Live Arena.
But Parker found success, landing some telling clean blows in a contest where the styles didn't complement each other, with constant grabbing disrupting the contest.
The officials scored it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They succeed," the victor commented in the ringside as he was faced disapproval from the crowd.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in February - to secure a 20th pro success.
Various analysts felt the challenger, thirty-one, deserved the decision but the Derbyshire fighter suffered the second loss of his 28-match professional journey.
Buatsi Claims Triumph in Dull Affair
His career development has plateaued in recent times through contract problems and extended periods of inactivity.
Previously predicted as the next star of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under recent support.
He opened tentatively, with neither fighter ready to take risks in a tentative opening few rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was participating in his second fight at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for the favorite, who utilized a tight guard to edge the more effective rounds.
The spectators' acceptance diminished amid regular grabbing, with Parker falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, ex-champion the boxing analyst - working with Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Hatton Memorial Fuels All-Manchester Contest
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a outstanding Manchester vs Manchester contest to secure the continental championship.
The venue fell silent for a deeply poignant tribute ahead of the contest as 10 bells rang in honor of local hero Ricky Hatton, who succumbed aged 46 in September.
It was the premier televised match card in the location since Hatton's death. As the concluding sound disappeared, the quiet became a chant of "there's only one Hatton".
The competition inside the ropes equaled the feeling. The eventual winner was knocked down by a left hook squarely on the chin in the initial stage, rising shakily to his feet on the eight count.
But the red-colored equipment of Arthur soon advanced again. From the other corner, the opponent - in competitive blue - was injured early, significant bruising developing under his face as the fighters landed hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the intensity hardly diminished over the full distance.
Arthur barely secured the decision with official scores of even score, narrow lead and 115-112, but each competitor were relentless and courageous, exactly what their inspiration the legend stood for.
