British light heavyweight Joshua Buatsi made a winning yet unimpressive start to his career under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a tight ten-round fight at the Co-op Live Arena.
But the challenger found success, landing some telling clean blows in a fight where the techniques didn't complement each other, with excessive holding spoiling the action.
The scoring judges scored it 96-94 for to the winner, with the third a even score.
"It wasn't my finest display but what defines champions? They win," Buatsi commented in the ringside as he was met by negative reactions from the audience.
The Londoner returned to winning ways after his initial pro loss - an epic battle with Callum Smith in February - to earn a 20th career victory.
Various analysts believed the challenger, 31, merited the decision but the Derbyshire fighter suffered the second setback of his 28-match career.
The Champion Claims Triumph in Dull Encounter
The fighter's advancement has stalled in the past few years through contract problems and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now finds himself trying to realize his potential - maybe in what appears to be a final roll of the dice - under recent support.
He started carefully, with neither fighter prepared to be aggressive in a calculated early stages.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was making just his second appearance at light heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for the favorite, who utilized a solid defense to barely take the more effective stanzas.
The crowd's patience diminished because of constant clinching, with Parker slipping to the canvas various instances during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. Although, ex-champion the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Homage Motivates All-Manchester Contest
In the supporting bout, Lyndon Arthur defeated Rea by divided decision in a excellent local rivalry battle to win the continental championship.
The venue grew hushed for a profoundly moving memorial before the fight as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who died 46 years old in recently.
It was the premier televised match card in the location since the passing of Hatton. As the last bell disappeared, the quiet transitioned to a chant of "there's only one Ricky Hatton".
The fighting inside the ropes reflected the emotion. The eventual winner was floored by a left hook flush on the chin in the initial stage, standing uncertainly to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was injured early, noticeable damage developing under his face as the fighters traded hard punches.
Rea, twenty-seven, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the pace rarely dropped over 12 rounds.
The victor narrowly won the decision with judges scorecards of 114-114, narrow lead and clearer margin, but both fighters were relentless and full of heart, everything their inspiration Hatton embodied.
