British light heavyweight Joshua Buatsi earned a win 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 appeared to earn him a judges' verdict in a tight ten-round fight at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective individual punches in a match where the techniques failed to mesh, with constant grabbing marring the contest.
Two judges had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my finest display but what do champions do? They win," Buatsi stated in the ring as he was met by disapproval from the spectators.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought Parker, thirty-one, merited the victory but the British boxer suffered the second setback of his 28-match professional journey.
The Champion Secures Win in Dull Affair
His career development has plateaued in the past few years through contract problems and extended periods of inactivity.
Previously predicted as the future of the British fight scene, he now stands trying to fulfil that early promise - maybe in what seems like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter prepared to overcommit in a tentative opening few rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after damaging his hand during the bout, was making just his second appearance at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who operated with a tight guard to narrowly win the more effective rounds.
The spectators' acceptance diminished amid constant clinching, with Parker falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but several stanzas were challenging to assess. However, previous titleholder the boxing analyst - providing analysis for Dazn - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
The victor advances, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Motivates All-Manchester Battle
In the co-main event, Arthur beat Bradley Rea by close verdict in a terrific Manchester vs Manchester contest to win the continental championship.
The venue grew hushed for a deeply poignant tribute before the fight as 10 bells rang in memory of the city's native Ricky Hatton, who passed away aged 46 in last month.
It was the premier televised match card in the urban center since the passing of Hatton. As the concluding sound faded, the stillness transitioned to a roar of "only one Ricky Hatton".
The action during the bout equaled the sentiment. The eventual winner was knocked down by a left hook squarely on the chin in the second round, rising shakily to his footing on the eight count.
But the red-colored shorts of the fighter soon came forward again. Across the ring, Rea - in rival City blue - was injured soon, heavy swelling developing under his face as the fighters landed powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the decision with official scores of 114-114, narrow lead and 115-112, but each competitor were determined and brave, all the qualities their idol the legend stood for.
