British light-heavyweight Joshua Buatsi made a winning yet underwhelming start to his career under new promoters with a points victory over Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a tight ten-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful clean blows in a match where the approaches didn't complement each other, with constant grabbing marring the fight.
Two judges scored it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest display but how do champions respond? They win," Buatsi said in the arena as he was met by negative reactions from the crowd.
The Londoner returned to winning ways after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts thought the challenger, 31, deserved the victory but the contender suffered the second setback of his 28-bout professional journey.
Buatsi Earns Triumph in Slow Affair
Buatsi's progress has stalled in the past few years through contract problems and extended periods of inactivity.
Previously predicted as the rising talent of the British fight scene, he now is positioned trying to realize his potential - perhaps in what seems like a final roll of the dice - under recent support.
He began cautiously, with neither fighter ready to take risks in a tentative early stages.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after breaking his hand during the bout, was making just his second bout at light-heavyweight.
By the halfway stage, Parker had made it competitive, creating difficulties for Buatsi, who operated with a tight guard to barely take the more effective periods.
The crowd's patience decreased amid regular grabbing, with Parker slipping to the canvas various instances during grappling.
Parker ended stronger, but several stanzas were difficult to score. However, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - on this evidence - still looks steep.
Hatton Homage Motivates All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Rea by split-decision in a excellent Manchester vs Manchester fight to win the continental belt.
The venue fell silent for a profoundly moving tribute before the fight as a bell ceremony rang in honor of the city's native Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the final chime faded, the stillness gave way to a shout of "there's just one Ricky Hatton".
The action during the bout reflected the sentiment. Arthur was sent to the canvas by a significant blow directly to the face in the second round, standing uncertainly to his position on the eight count.
But the red-colored attire of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was marked up quickly, heavy swelling developing under his orbital area as the fighters traded punishing blows.
The challenger, twenty-seven, landed power punches but the champion, 34, responded in kind with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor edged the result with official scores of even score, 115-113 and clearer margin, but the two athletes were relentless and brave, everything their hero Hatton embodied.
