UK light heavyweight Joshua Buatsi earned a win yet underwhelming debut to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a tight ten-round contest at the Manchester venue.
But Parker had his moments, connecting with powerful individual punches in a fight where the styles didn't complement each other, with frequent clinching spoiling the action.
Two judges had it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my finest display but what do champions do? They prevail," Buatsi stated in the ring as he was faced negative reactions from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with Callum Smith in February - to earn a 20th pro success.
Several boxing experts felt Parker, thirty-one, merited the win but the contender experienced the second defeat of his 28-fight professional journey.
Buatsi Secures Triumph in Dull Match
His career development has stalled in recent years through contract problems and extended periods of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - maybe in what feels like a last chance - under new promotional backing.
He opened tentatively, with both competitors prepared to take risks in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in 2022 after damaging his hand in the contest, was making just his second bout at the higher weight class.
By the halfway stage, Parker had stayed in contention, making life awkward for Buatsi, who utilized a tight guard to barely take the better periods.
The spectators' acceptance diminished amid constant clinching, with Parker falling to the floor several times during clinches.
Parker closed well, but several stanzas were challenging to assess. Nevertheless, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just one round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Tribute Motivates Manchester Derby Fight
In the secondary fight, Arthur beat Bradley Rea by divided decision in a outstanding Manchester vs Manchester battle to capture the European light-heavyweight title.
The arena became quiet for a extremely emotional memorial before the fight as ten bells sounded in honor of local hero Ricky Hatton, who succumbed at age 46 in September.
It was the first major televised match card in the location since the passing of Hatton. As the final chime faded, the stillness transitioned to a chant of "there's just one Hatton".
The competition during the bout reflected the emotion. Arthur was floored by a significant blow directly to the chin in the early round, standing uncertainly to his feet on the referee's count.
But the Manchester United-red shorts of Arthur soon came forward again. Across the ring, Rea - in rival City blue - was injured early, significant bruising appearing under his orbital area as the pair traded hard punches.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with stinging uppercuts as the intensity rarely dropped over twelve rounds.
Arthur barely secured the result with judges scorecards of even score, close margin and clearer margin, but the two athletes were relentless and full of heart, all the qualities their idol the legend embodied.
