UK light-heavyweight Joshua Buatsi made a winning yet disappointing start to life under fresh promotional backing with a points victory over Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a split decision in a tight ten-round contest at the boxing arena.
But Parker had his moments, connecting with powerful clean blows in a contest where the approaches failed to mesh, with constant grabbing marring the contest.
The scoring judges had it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my finest display but what do champions do? They prevail," the victor commented in the arena as he was met by negative reactions from the spectators.
The British fighter got back to winning after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a twentieth professional win.
Various analysts felt Parker, 31, deserved the decision but the Derbyshire fighter suffered the second defeat of his 28-match career.
The Champion Secures Victory in Dull Encounter
The fighter's advancement has slowed in the past few years through management issues and extended periods of inactivity.
Previously predicted as the next star of the British fight scene, he now is positioned trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He started carefully, with the two boxers prepared to take risks in a tentative early stages.
The challenger, whose single earlier setback came at super-middleweight 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 kept it close, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the cleaner stanzas.
The crowd's patience decreased during frequent holding, with the challenger falling to the floor various instances during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the presence of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Hatton Homage Motivates Local Rivalry Battle
In the secondary fight, Arthur defeated Rea by divided decision in a terrific Manchester vs Manchester battle to capture the European light-heavyweight title.
The stadium fell silent for a extremely emotional homage ahead of the contest as 10 bells sounded in honor of Manchester's own Hatton, who passed away 46 years old in last month.
It was the premier televised boxing event in the city since the passing of Hatton. As the concluding sound disappeared, the silence transitioned to a chant of "there's only one Hatton".
The action within the ring reflected the sentiment. The eventual winner was floored by a powerful punch flush on the face in the early round, standing uncertainly to his footing on the referee's count.
But the traditional red equipment of Arthur soon came forward again. From the other corner, the opponent - in opposing blue - was marked up quickly, noticeable damage forming under his eye as the duo landed punishing blows.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the action seldom decreased over 12 rounds.
Arthur barely secured the verdict with judges scorecards of 114-114, 115-113 and 115-112, but each competitor were relentless and full of heart, all the qualities their inspiration Hatton embodied.
