British light-heavyweight Joshua Buatsi earned a win yet unimpressive beginning to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a close 10-round fight at the boxing arena.
But Parker landed significant shots, delivering effective clean blows in a contest where the approaches failed to mesh, with frequent clinching marring the fight.
The scoring judges scored it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my best performance but what defines champions? They prevail," the victor commented in the ringside as he was met by negative reactions from the crowd.
The Londoner bounced back after his first professional defeat - an thrilling contest with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers felt the challenger, thirty-one, deserved the victory but the Derbyshire fighter experienced the second defeat of his 28-bout career.
The Champion Claims Win in Slow Encounter
Buatsi's progress has slowed in recent times through contract problems and extended periods of lack of fights.
Once tipped as the future of the British fight scene, he now finds himself trying to realize his potential - maybe in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with both competitors willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was participating in his second fight at light-heavyweight.
By the halfway stage, the underdog had kept it close, creating difficulties for Buatsi, who worked behind a tight guard to narrowly win the better stanzas.
The crowd's patience decreased during regular grabbing, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog closed well, but several stanzas were hard to judge. Nevertheless, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the presence of hard hitter Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Tribute Fuels Local Rivalry Fight
In the supporting bout, Arthur beat Rea by close verdict in a excellent local rivalry contest to capture the European light-heavyweight title.
The venue fell silent for a deeply poignant homage ahead of the contest as a bell ceremony tolled in honor of Manchester's own Ricky Hatton, who died 46 years old in September.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the last bell faded, the quiet gave way to a roar of "there's just one Hatton".
The action during the bout reflected the emotion. Arthur was knocked down by a powerful punch flush on the jaw in the initial stage, rising shakily to his footing on the count of eight.
But the Manchester United-red shorts of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was marked up quickly, noticeable damage developing under his orbital area as the pair traded punishing blows.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the intensity seldom decreased over the full distance.
Arthur edged the verdict with judges scorecards of draw, close margin and 115-112, but both fighters were determined and full of heart, exactly what their idol the legend embodied.
