UK light heavyweight Joshua Buatsi secured a victory yet unimpressive start to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a majority decision in a close ten-round bout at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful individual punches in a fight where the techniques failed to mesh, with frequent clinching spoiling the action.
The scoring judges scored it 96-94 to Buatsi, with the final judge a 95-95.
"It wasn't my finest display but what do champions do? They win," Buatsi said in the ring as he was faced disapproval from the crowd.
The Londoner bounced back after his first professional defeat - an thrilling contest with Callum Smith in last winter - to claim a 20th pro success.
Several boxing experts felt the challenger, 31, deserved the decision but the Derbyshire fighter suffered the second setback of his 28-match professional journey.
Buatsi Secures Win in Uneventful Match
Buatsi's progress has stalled in recent years through promotional disputes and long spells of lack of fights.
Once tipped as the future of British boxing, he now finds himself trying to realize his potential - perhaps in what seems like a ultimate opportunity - under recent support.
He opened tentatively, with the two boxers willing to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was making just his second fight at the higher weight class.
By the fight's midpoint, Parker had kept it close, causing problems for Buatsi, who worked behind a tight guard to narrowly win the better stanzas.
The crowd's patience diminished because of regular grabbing, with the challenger going down several times during grappling.
Parker ended stronger, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor progresses, but with the caliber of power puncher David Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Homage Inspires All-Manchester Contest
In the secondary fight, Arthur defeated Rea by close verdict in a terrific Manchester vs Manchester fight to secure the continental title.
The arena grew hushed for a profoundly moving tribute prior to the bout as a bell ceremony tolled in remembrance of the city's native Hatton, who passed away 46 years old in last month.
It was the premier televised fight night in the city since Hatton's passing. As the final chime faded, the silence gave way to a shout of "there's just one Ricky Hatton".
The fighting within the ring matched the sentiment. The eventual winner was floored by a significant blow squarely on the face in the early round, standing uncertainly to his footing on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was damaged soon, noticeable damage appearing under his face as the pair exchanged powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the pace seldom decreased over twelve rounds.
The victor narrowly won the result with official scores of even score, narrow lead and wider gap, but the two athletes were determined and full of heart, exactly what their hero Hatton embodied.
