British light heavyweight Joshua Buatsi made a winning yet disappointing start to life under recent management with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a majority decision in a tight ten-round fight at the Manchester venue.
But Parker had his moments, landing some telling individual punches in a contest where the techniques didn't complement each other, with constant grabbing marring the contest.
The scoring judges scored it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi commented in the ringside as he was met by boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in February - to secure a 20th career victory.
Some ringside observers felt the challenger, 31, should have been awarded the win but the contender experienced the second loss of his 28-fight career.
The Champion Claims Victory in Slow Match
The fighter's advancement has plateaued in the past few years through contract problems and extended periods of lack of fights.
Once tipped as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what appears to be a last chance - under recent support.
He began cautiously, with the two boxers willing to overcommit in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after breaking his hand mid-fight, was making just his second bout at the higher weight class.
By the middle rounds, the underdog had kept it close, making life awkward for Buatsi, who utilized a solid defense to barely take the better periods.
The spectators' acceptance wore thin amid frequent holding, with the challenger going down multiple occasions during close exchanges.
Parker closed well, but multiple periods were hard to judge. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi progresses, but with the presence of power puncher David Benavidez, and Russian champion Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Arthur defeated Rea by split-decision in a excellent local rivalry contest to secure the European light-heavyweight title.
The stadium fell silent for a extremely emotional memorial ahead of the contest as a bell ceremony rang in honor of Manchester's own Ricky Hatton, who succumbed at age 46 in September.
It was the premier televised fight night in the city since Hatton's passing. As the concluding sound disappeared, the silence gave way to a shout of "there's just one Hatton".
The fighting within the ring reflected the feeling. The eventual winner was floored by a significant blow squarely on the jaw in the early round, getting up unsteadily to his footing on the eight count.
But the red-colored shorts of the fighter soon advanced again. On the opposite side, the opponent - in rival City blue - was damaged soon, heavy swelling developing under his orbital area as the duo landed powerful shots.
The challenger, 27, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the action rarely dropped over the full distance.
The victor narrowly won the result with scoring tallies of draw, narrow lead and clearer margin, but both fighters were persistent and brave, everything their hero the legend represented.
