British light-heavyweight Joshua Buatsi earned a win yet underwhelming beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a majority decision in a competitive ten-round bout at the Manchester venue.
But the challenger landed significant shots, landing some telling clean blows in a match where the styles didn't complement each other, with constant grabbing spoiling the fight.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my greatest showing but how do champions respond? They win," the victor said in the arena as he was greeted with disapproval from the audience.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in last winter - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, deserved the decision but the British boxer endured the second setback of his 28-bout professional journey.
Buatsi Secures Triumph in Dull Affair
The fighter's advancement has stalled in recent times through management issues and considerable time of lack of fights.
Earlier forecast as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a last chance - under fresh management.
He began cautiously, with the two boxers ready to take risks in a calculated opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second fight at light heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who utilized a tight guard to barely take the more effective rounds.
The spectators' acceptance decreased amid frequent holding, with the challenger slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but multiple periods were challenging to assess. Although, former world champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the likes of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Tribute Inspires All-Manchester Fight
In the secondary fight, Lyndon Arthur defeated Rea by split-decision in a terrific local rivalry battle to win the continental title.
The arena grew hushed for a profoundly moving tribute ahead of the contest as ten bells sounded in honor of local hero Ricky Hatton, who died aged 46 in recently.
It was the first major televised fight night in the urban center since Hatton's passing. As the last bell disappeared, the quiet transitioned to a shout of "there's just one Ricky Hatton".
The action within the ring reflected the emotion. Arthur was floored by a left hook flush on the jaw in the early round, standing uncertainly to his footing on the eight count.
But the red-colored shorts of Arthur soon advanced again. From the other corner, Rea - in opposing blue - was damaged quickly, noticeable damage appearing under his face as the duo exchanged hard punches.
The challenger, twenty-seven, landed power punches but the champion, 34, fought fire with fire with powerful upward punches as the action seldom decreased over the full distance.
The victor narrowly won the verdict with official scores of draw, 115-113 and 115-112, but each competitor were relentless and courageous, all the qualities their idol the legend represented.
