British light heavyweight Joshua Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a split decision in a close 10-round contest at the Manchester venue.
But the challenger landed significant shots, connecting with powerful clean blows in a fight where the styles never quite clicked, with constant grabbing marring the fight.
Two judges scored it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my finest display but what defines champions? They win," Buatsi commented in the arena as he was met by negative reactions from the spectators.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in February - to secure a twentieth professional win.
Various analysts believed the challenger, thirty-one, deserved the decision but the contender experienced the second setback of his 28-match professional journey.
Buatsi Secures Triumph in Dull Affair
His career development has plateaued in recent years through promotional disputes and long spells of lack of fights.
Earlier forecast as the future of the British fight scene, he now stands trying to realize his potential - maybe in what appears to be a last chance - under recent support.
He started carefully, with neither fighter willing to take risks in a cagey early stages.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second appearance at the higher weight class.
By the fight's midpoint, Parker had made it competitive, making life awkward for Buatsi, who utilized a tight guard to edge the more effective rounds.
The audience's tolerance wore thin during constant clinching, with the challenger going down various instances during close exchanges.
Parker ended stronger, but multiple periods were challenging to assess. Although, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - judging by this showing - still seems difficult.
Hatton Tribute Fuels Local Rivalry Fight
In the secondary fight, Lyndon Arthur defeated Bradley Rea by close verdict in a outstanding Manchester vs Manchester battle to capture the continental title.
The venue fell silent for a extremely emotional tribute ahead of the contest as 10 bells rang in honor of local hero Hatton, who died at age 46 in September.
It was the first major televised match card in the location since Hatton's passing. As the final chime faded, the stillness became a shout of "only one Ricky Hatton".
The action inside the ropes reflected the feeling. The eventual winner was knocked down by a powerful punch squarely on the face in the initial stage, rising shakily to his position on the referee's count.
But the red-colored equipment of the fighter soon advanced again. On the opposite side, the opponent - in opposing blue - was marked up early, significant bruising forming under his eye as the fighters traded powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with effective uppercuts as the pace hardly diminished over 12 rounds.
The victor edged the verdict with judges scorecards of even score, narrow lead and wider gap, but each competitor were persistent and brave, all the qualities their idol Hatton embodied.
