British light-heavyweight Joshua Buatsi earned a win yet unimpressive beginning to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a close ten-round contest at the Co-op Live Arena.
But Parker had his moments, landing some telling clean blows in a fight where the approaches didn't complement each other, with frequent clinching marring the fight.
Two judges had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They prevail," Buatsi commented in the ring as he was greeted with disapproval from the spectators.
The British fighter got back to winning after his first professional defeat - an thrilling contest with his previous opponent in February - to earn a 20th career victory.
Various analysts felt Parker, thirty-one, deserved the victory but the British boxer suffered the second loss of his 28-bout professional journey.
Buatsi Claims Victory in Uneventful Affair
His career development has stalled in the past few years through contract problems and extended periods of inactivity.
Previously predicted as the next star of British boxing, he now stands trying to achieve expectations - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers prepared to overcommit in a cagey initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was participating in his second bout at the higher weight class.
By the halfway stage, the underdog had made it competitive, causing problems for Buatsi, who operated with a tight guard to edge the better rounds.
The spectators' acceptance wore thin amid frequent holding, with the challenger going down several times during close exchanges.
Parker closed well, but multiple periods were difficult to score. Nevertheless, former world champion the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
The victor moves on, but with the likes of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Battle
In the co-main event, Arthur beat Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to secure the continental belt.
The arena grew hushed for a extremely emotional homage ahead of the contest as a bell ceremony tolled in honor of local hero Ricky Hatton, who died 46 years old in recently.
It was the premier televised boxing event in the city since the passing of Hatton. As the last bell ended, the stillness gave way to a chant of "there's just one Hatton".
The fighting within the ring matched the sentiment. The eventual winner was knocked down by a significant blow flush on the jaw in the second round, rising shakily to his position on the eight count.
But the traditional red shorts of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was injured quickly, noticeable damage developing under his face as the duo landed powerful shots.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with stinging uppercuts as the pace seldom decreased over the full distance.
The victor edged the decision with official scores of draw, narrow lead and wider gap, but each competitor were relentless and courageous, exactly what their idol Hatton embodied.
