British light heavyweight Joshua Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a close 10-round contest at the boxing arena.
But the challenger found success, connecting with powerful clean blows in a fight where the approaches failed to mesh, with excessive holding marring the action.
The scoring judges had it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my finest performance but what defines champions? They win," the victor stated in the ringside as he was met by disapproval from the audience.
The Londoner got back to winning after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a twentieth professional win.
Various analysts believed Parker, thirty-one, deserved the win but the contender experienced the second setback of his 28-bout professional journey.
Buatsi Claims Win in Dull Encounter
Buatsi's progress has stalled in recent years through contract problems and considerable time of inactivity.
Once tipped as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with neither fighter ready to be aggressive in a cagey initial rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand in the contest, was participating in his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who utilized a protective stance to narrowly win the more effective periods.
The audience's tolerance decreased because of regular grabbing, with the challenger going down multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were challenging to assess. Nevertheless, previous titleholder Carl Frampton - working with the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just one round.
The victor moves on, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Memorial Fuels Local Rivalry Contest
In the co-main event, Arthur overcame Rea by close verdict in a terrific local rivalry battle to secure the continental championship.
The arena grew hushed for a profoundly moving tribute prior to the bout as a bell ceremony rang in memory of Manchester's own Hatton, who died at age 46 in September.
It was the first major televised match card in the urban center since Hatton's passing. As the last bell ended, the silence gave way to a roar of "there's only one Ricky Hatton".
The competition inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a left hook directly to the jaw in the early round, getting up unsteadily to his position on the eight count.
But the traditional red attire of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was injured early, heavy swelling forming under his face as the fighters landed powerful shots.
Rea, 27, landed power punches but Arthur, thirty-four, matched the intensity with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur edged the verdict with judges scorecards of 114-114, narrow lead and wider gap, but the two athletes were persistent and full of heart, exactly what their hero the legend stood for.
