British light heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to life under fresh promotional backing with a decision win over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a split decision in a competitive 10-round contest at the Co-op Live Arena.
But Parker found success, delivering effective single shots in a contest where the approaches failed to mesh, with frequent clinching disrupting the action.
Two judges judged it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," the victor said in the ringside as he was faced negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an memorable fight 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 decision but the Derbyshire fighter endured the second setback of his 28-fight career.
Buatsi Claims Win in Uneventful Affair
The fighter's advancement has slowed in recent years through management issues and extended periods of inactivity.
Earlier forecast as the next star of UK boxing, he now stands trying to fulfil that early promise - possibly in what feels like a last chance - under new promotional backing.
He started carefully, with both competitors willing to be aggressive in a cagey opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after breaking his hand mid-fight, was making just his second bout at light heavyweight.
By the middle rounds, the underdog had made it competitive, making life awkward for Buatsi, who utilized a tight guard to barely take the cleaner rounds.
The crowd's patience diminished during regular grabbing, with Parker falling to the floor various instances during grappling.
Parker finished the stronger, but many rounds were difficult to score. Although, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor advances, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Memorial Fuels Manchester Derby Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester battle to capture the continental championship.
The venue grew hushed for a deeply poignant memorial prior to the bout as 10 bells tolled in memory of the city's native Hatton, who died 46 years old in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the last bell faded, the quiet gave way to a shout of "only one Ricky Hatton".
The action within the ring reflected the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the face in the initial stage, getting up unsteadily to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon came forward again. On the opposite side, the opponent - in competitive blue - was marked up soon, significant bruising developing under his face as the pair exchanged punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, responded in kind with powerful upward punches as the action rarely dropped over 12 rounds.
Arthur barely secured the result with judges scorecards of even score, 115-113 and clearer margin, but both fighters were relentless and full of heart, exactly what their idol Hatton embodied.
