British light-heavyweight Joshua Buatsi earned a win yet unimpressive start to life under recent management with a decision win over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a competitive 10-round fight at the boxing arena.
But the challenger had his moments, delivering effective individual punches in a match where the techniques never quite clicked, with excessive holding marring the action.
The scoring judges scored it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best performance but what defines champions? They prevail," Buatsi commented in the ring as he was met by boos from the spectators.
The British fighter got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to claim a twentieth professional win.
Various analysts believed the challenger, thirty-one, merited the decision but the British boxer suffered the second defeat of his 28-match professional journey.
Buatsi Secures Win in Slow Match
The fighter's advancement has slowed in the past few years through promotional disputes and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now is positioned trying to achieve expectations - maybe in what seems like a last chance - under new promotional backing.
He opened tentatively, with both competitors willing to take risks in a tentative early stages.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second fight at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, causing problems for Buatsi, who worked behind a protective stance to barely take the more effective stanzas.
The spectators' acceptance diminished during regular grabbing, with Parker going down multiple occasions during grappling.
The underdog finished the stronger, but multiple periods were hard to judge. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher David Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires All-Manchester Fight
In the secondary fight, Lyndon Arthur beat Rea by close verdict in a terrific local rivalry fight to secure the continental belt.
The arena became quiet for a deeply poignant homage prior to the bout as ten bells rang in remembrance of Manchester's own Ricky Hatton, who passed away at age 46 in September.
It was the first major televised boxing event in the city since Hatton's death. As the final chime ended, the silence gave way to a roar of "only one Hatton".
The fighting inside the ropes equaled the feeling. The eventual winner was knocked down by a significant blow squarely on the face in the second round, rising shakily to his position on the count of eight.
But the red-colored shorts of Arthur soon came forward again. Across the ring, Rea - in opposing blue - was injured quickly, heavy swelling forming under his orbital area as the pair exchanged hard punches.
Rea, 27, delivered effective strikes but the champion, thirty-four, responded in kind with powerful upward punches as the pace seldom decreased over twelve rounds.
Arthur narrowly won the verdict with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were persistent and brave, everything their hero the legend represented.
