British light heavyweight Joshua Buatsi earned a win yet underwhelming start to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a tight 10-round contest at the Manchester venue.
But the challenger landed significant shots, delivering effective single shots in a contest where the styles never quite clicked, with frequent clinching spoiling the fight.
The officials had it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my best display but what defines champions? They win," Buatsi stated in the ringside as he was met by disapproval from the spectators.
The British fighter got back to winning after his initial pro loss - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Various analysts thought Parker, 31, merited the victory but the Derbyshire fighter suffered the second loss of his 28-bout professional journey.
Buatsi Secures Victory in Uneventful Encounter
Buatsi's progress has slowed in recent years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers ready to take risks in a tentative opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was making just his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for the favorite, who utilized a protective stance to narrowly win the more effective rounds.
The spectators' acceptance diminished because of frequent holding, with Parker going down multiple occasions during clinches.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion Carl Frampton - commentating on Dazn - had it significantly in favor for Parker, awarding Buatsi just one round.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Russian champion Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Hatton Tribute Fuels All-Manchester Fight
In the co-main event, Arthur defeated Rea by close verdict in a excellent local rivalry fight to capture the European light-heavyweight championship.
The venue grew hushed for a profoundly moving memorial before the fight as ten bells sounded in remembrance of local hero Ricky Hatton, who passed away 46 years old in last month.
It was the first major televised fight night in the city since the passing of Hatton. As the concluding sound ended, the quiet transitioned to a shout of "only one Hatton".
The competition inside the ropes reflected the feeling. Arthur was floored by a left hook flush on the face in the early round, rising shakily to his footing on the eight count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, Rea - in competitive blue - was damaged quickly, significant bruising appearing under his orbital area as the duo traded powerful shots.
Rea, 27, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
The victor edged the verdict with scoring tallies of 114-114, close margin and 115-112, but the two athletes were relentless and courageous, all the qualities their idol Hatton embodied.
