British light heavyweight Joshua Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a split decision in a competitive ten-round bout at the Manchester venue.
But the challenger landed significant shots, landing some telling individual punches in a match where the techniques never quite clicked, with excessive holding spoiling the fight.
The scoring judges scored it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my greatest performance but what do champions do? They win," the victor stated in the ring as he was greeted with boos from the crowd.
The British fighter got back to winning after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Some ringside observers thought the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter endured the second setback of his 28-match professional journey.
Buatsi Earns Win in Dull Match
The fighter's advancement has stalled in the past few years through promotional disputes and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to achieve expectations - maybe in what feels like a ultimate opportunity - under fresh management.
He started carefully, with both competitors ready to be aggressive in a calculated 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 fight at light heavyweight.
By the halfway stage, the underdog had kept it close, making life awkward for the favorite, who utilized a tight guard to barely take the better stanzas.
The audience's tolerance diminished amid constant clinching, with Parker falling to the floor multiple occasions during grappling.
The underdog ended stronger, but multiple periods were challenging to assess. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Fuels Manchester Derby Battle
In the secondary fight, Lyndon Arthur overcame Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to secure the European light-heavyweight title.
The arena grew hushed for a profoundly moving memorial prior to the bout as a bell ceremony tolled in memory of the city's native Ricky Hatton, who died aged 46 in September.
It was the first major televised fight night in the city since Hatton's passing. As the final chime disappeared, the quiet transitioned to a chant of "there's only one Hatton".
The fighting within the ring matched the sentiment. The eventual winner was floored by a significant blow directly to the chin in the initial stage, rising shakily to his position on the eight count.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, the opponent - in competitive blue - was damaged quickly, significant bruising forming under his orbital area as the duo landed punishing blows.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with powerful upward punches as the action seldom decreased over 12 rounds.
Arthur barely secured the result with official scores of 114-114, narrow lead and wider gap, but each competitor were relentless and full of heart, all the qualities their idol Hatton stood for.
