UK light heavyweight Joshua Buatsi made a winning yet disappointing beginning to life under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a split decision in a competitive 10-round bout at the boxing arena.
But the challenger found success, delivering effective individual punches in a match where the approaches failed to mesh, with constant grabbing disrupting the contest.
The officials judged it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my best display but what do champions do? They succeed," Buatsi stated in the ringside as he was faced negative reactions from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Various analysts thought the challenger, 31, merited the victory but the British boxer experienced the second defeat of his 28-match career.
Buatsi Secures Victory in Dull Affair
Buatsi's progress has slowed in recent years through promotional disputes and considerable time of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to achieve expectations - maybe in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors willing to overcommit in a tentative opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at light-heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who operated with a solid defense to edge the more effective stanzas.
The crowd's patience decreased because of frequent holding, with the challenger going down multiple occasions during grappling.
Parker closed well, but multiple periods were challenging to assess. Although, previous titleholder the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the caliber of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - based on this performance - still appears challenging.
Hatton Tribute Motivates Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester fight to secure the European light heavyweight belt.
The venue fell silent for a deeply poignant homage before the fight as a bell ceremony sounded in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the first major televised match card in the location since the passing of Hatton. As the final chime disappeared, the quiet transitioned to a roar of "only one Ricky Hatton".
The action within the ring equaled the feeling. Arthur was sent to the canvas by a left hook flush on the chin in the initial stage, standing uncertainly to his feet on the eight count.
But the Manchester United-red attire of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was injured quickly, significant bruising appearing under his face as the fighters traded punishing blows.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace rarely dropped over twelve rounds.
Arthur edged the result with scoring tallies of 114-114, narrow lead and clearer margin, but the two athletes were determined and brave, everything their idol the legend represented.
