British light heavyweight Joshua Buatsi earned a win yet underwhelming beginning to life under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a close 10-round contest at the Manchester venue.
But Parker found success, landing some telling individual punches in a fight where the approaches didn't complement each other, with constant grabbing marring the contest.
The scoring judges scored it 96-94 for to the winner, with the third a 95-95.
"It wasn't my finest display but what do champions do? They win," Buatsi said in the ring as he was met by boos from the spectators.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Various analysts believed the challenger, thirty-one, deserved the decision but the Derbyshire fighter suffered the second loss of his 28-fight professional journey.
The Champion Secures Victory in Dull Match
The fighter's advancement has slowed in recent years through management issues and extended periods of inactivity.
Previously predicted as the next star of the British fight scene, he now finds himself trying to achieve expectations - maybe in what seems like a ultimate opportunity - under recent support.
He opened tentatively, with neither fighter ready to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after suffering a hand injury in the contest, was participating in his second bout at light heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who utilized a tight guard to barely take the better rounds.
The audience's tolerance wore thin during regular grabbing, with the challenger falling to the floor several times during grappling.
Parker ended stronger, but many rounds were difficult to score. However, previous titleholder the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian star Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a outstanding Manchester vs Manchester fight to capture the European light heavyweight championship.
The arena grew hushed for a deeply poignant tribute ahead of the contest as 10 bells tolled in remembrance of local hero Hatton, who died at age 46 in recently.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell faded, the quiet gave way to a chant of "only one Hatton".
The competition within the ring equaled the feeling. The eventual winner was floored by a significant blow flush on the jaw in the second round, getting up unsteadily to his feet on the count of eight.
But the Manchester United-red equipment of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was marked up soon, heavy swelling forming under his orbital area as the pair traded punishing blows.
The challenger, 27, landed power punches but Arthur, thirty-four, matched the intensity with stinging uppercuts as the action hardly diminished over twelve rounds.
Arthur edged the verdict with official scores of draw, 115-113 and wider gap, but each competitor were relentless and brave, exactly what their inspiration Hatton embodied.
