British light heavyweight Joshua Buatsi secured a victory yet unimpressive debut to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a competitive 10-round bout at the boxing arena.
But Parker landed significant shots, connecting with powerful clean blows in a contest where the styles never quite clicked, with frequent clinching disrupting the contest.
Two judges scored it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi stated in the arena as he was met by disapproval from the spectators.
The British fighter got back to winning after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a 20th pro success.
Various analysts felt Parker, 31, deserved the decision but the Derbyshire fighter endured the second setback of his 28-bout career.
Buatsi Claims Triumph in Dull Affair
The fighter's advancement has plateaued in recent years through management issues and extended periods of lack of fights.
Once tipped as the future of British boxing, he now is positioned trying to fulfil that early promise - possibly in what feels like a final roll of the dice - under recent support.
He started carefully, with both competitors willing to take risks in a cagey opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was making just his second bout at light heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for Buatsi, who utilized a tight guard to edge the cleaner stanzas.
The crowd's patience wore thin during regular grabbing, with Parker falling to the floor several times during clinches.
The underdog closed well, but several stanzas were difficult to score. Nevertheless, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - judging by this showing - still appears challenging.
Hatton Homage Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur beat Bradley Rea by split-decision in a terrific local rivalry contest to capture the European light heavyweight belt.
The venue fell silent for a extremely emotional tribute before the fight as a bell ceremony rang in honor of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the first major televised fight night in the city since Hatton's death. As the last bell faded, the quiet became a roar of "there's just one Hatton".
The competition inside the ropes matched the sentiment. Arthur was sent to the canvas by a left hook directly to the jaw in the second round, standing uncertainly to his position on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. Across the ring, the opponent - in rival City blue - was damaged quickly, significant bruising developing under his orbital area as the fighters exchanged powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the pace hardly diminished over the full distance.
The victor barely secured the verdict with judges scorecards of draw, 115-113 and clearer margin, but the two athletes were persistent and full of heart, exactly what their inspiration the legend stood for.
