UK light-heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to life under recent management with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a competitive 10-round contest at the Co-op Live Arena.
But the challenger found success, landing some telling individual punches in a contest where the styles didn't complement each other, with constant grabbing marring the fight.
Two judges had it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my best performance but how do champions respond? They win," the victor stated in the arena as he was met by negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the victory but the contender experienced the second defeat of his 28-bout professional journey.
Buatsi Claims Triumph in Dull Affair
The fighter's advancement has plateaued in recent years through management issues and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to realize his potential - maybe in what appears to be a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to be aggressive in a cagey opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand in the contest, was making just his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who operated with a tight guard to edge the cleaner stanzas.
The spectators' acceptance diminished during regular grabbing, with Parker going down various instances during clinches.
The underdog ended stronger, but many rounds were difficult to score. However, ex-champion the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the caliber of heavy hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Hatton Tribute Motivates Manchester Derby Fight
In the secondary fight, Lyndon Arthur beat Rea by divided decision in a excellent all-Manchester battle to win the European light heavyweight belt.
The stadium fell silent for a profoundly moving homage before the fight as ten bells tolled in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the premier televised match card in the location since the passing of Hatton. As the last bell ended, the stillness transitioned to a shout of "there's only one Ricky Hatton".
The competition during the bout matched the emotion. The eventual winner was sent to the canvas by a significant blow flush on the chin in the second round, rising shakily to his footing on the count of eight.
But the traditional red attire of Arthur soon came forward again. On the opposite side, the opponent - in rival City blue - was damaged early, significant bruising appearing under his orbital area as the fighters landed punishing blows.
Rea, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with powerful upward punches as the action rarely dropped over the full distance.
The victor edged the verdict with judges scorecards of 114-114, 115-113 and clearer margin, but each competitor were relentless and brave, all the qualities their hero the legend represented.
