British light heavyweight Joshua Buatsi earned a win yet unimpressive start to his career under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close ten-round fight at the boxing arena.
But Parker landed significant shots, connecting with powerful individual punches in a match where the approaches failed to mesh, with excessive holding disrupting the action.
The scoring judges had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my best display but what defines champions? They win," Buatsi commented in the ringside as he was met by negative reactions from the spectators.
The Londoner bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Some ringside observers felt the challenger, 31, deserved the decision but the British boxer experienced the second setback of his 28-fight career.
Buatsi Secures Win in Uneventful Affair
His career development has stalled in recent years through promotional disputes and long spells of lack of fights.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to realize his potential - maybe in what seems like a final roll of the dice - under recent support.
He began cautiously, with both competitors prepared to overcommit in a calculated opening few rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the middle rounds, the underdog had kept it close, causing problems for the favorite, who worked behind a solid defense to narrowly win the better rounds.
The spectators' acceptance diminished amid regular grabbing, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog finished the stronger, but multiple periods were hard to judge. Although, previous titleholder the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor progresses, but with the likes of power puncher Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - judging by this showing - still appears challenging.
Hatton Homage Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur defeated Rea by divided decision in a terrific all-Manchester battle to win the European light heavyweight championship.
The stadium grew hushed for a deeply poignant memorial prior to the bout as a bell ceremony rang in memory of Manchester's own Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the last bell ended, the stillness gave way to a shout of "only one Hatton".
The action within the ring matched the sentiment. The eventual winner was sent to the canvas by a powerful punch flush on the jaw in the initial stage, standing uncertainly to his feet on the count of eight.
But the red-colored shorts of Arthur soon pressed ahead again. On the opposite side, Rea - in rival City blue - was damaged soon, significant bruising appearing under his face as the duo exchanged powerful shots.
Rea, 27, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
Arthur barely secured the result with official scores of even score, close margin and clearer margin, but each competitor were relentless and full of heart, everything their idol Hatton stood for.
