UK light-heavyweight Joshua Buatsi earned a win 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 work rate seemingly secured him a majority decision in a competitive ten-round contest at the Manchester venue.
But the challenger found success, delivering effective clean blows in a fight where the styles didn't complement each other, with frequent clinching spoiling the contest.
The scoring judges scored it 96-94 for to the winner, with the remaining official a 95-95.
"It wasn't my best performance but what defines champions? They succeed," the victor commented in the arena as he was greeted with boos from the spectators.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Various analysts thought the challenger, 31, should have been awarded the victory but the contender endured the second setback of his 28-match career.
The Champion Secures Triumph in Slow Affair
His career development has stalled in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now is positioned trying to realize his potential - possibly in what appears to be a final roll of the dice - under fresh management.
He started carefully, with both competitors ready to take risks in a calculated opening few rounds.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after damaging 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, creating difficulties for the favorite, who operated with a solid defense to narrowly win the cleaner rounds.
The spectators' acceptance diminished during regular grabbing, with Parker slipping to the canvas various instances during clinches.
Parker closed well, but several stanzas were challenging to assess. Although, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor progresses, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Hatton Tribute Motivates All-Manchester Contest
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a outstanding local rivalry contest to secure the continental belt.
The venue grew hushed for a deeply poignant memorial before the fight as ten bells sounded in honor of local hero Hatton, who died aged 46 in last month.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the concluding sound disappeared, the stillness gave way to a shout of "only one Ricky Hatton".
The competition inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the face in the early round, standing uncertainly to his footing on the count of eight.
But the traditional red shorts of the fighter soon came forward again. Across the ring, Rea - in opposing blue - was marked up soon, noticeable damage developing under his face as the duo landed punishing blows.
The challenger, 27, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the action seldom decreased over twelve rounds.
The victor barely secured the verdict with judges scorecards of even score, close margin and clearer margin, but the two athletes were persistent and courageous, all the qualities their hero the legend embodied.
