UK light-heavyweight Joshua Buatsi earned a win yet unimpressive debut to his career under recent management with a decision win over Parker in Manchester.
The Olympic medal winner's punch output likely gained him a split decision in a competitive ten-round fight at the Co-op Live Arena.
But the challenger had his moments, landing some telling clean blows in a fight where the approaches didn't complement each other, with excessive holding disrupting the action.
The scoring judges scored it 96-94 for to the winner, with the final judge a even score.
"It wasn't my finest display but how do champions respond? They succeed," the victor commented in the ringside as he was met by disapproval from the spectators.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a twentieth professional win.
Various analysts thought the challenger, thirty-one, deserved the decision but the contender experienced the second defeat of his 28-bout career.
Buatsi Secures Triumph in Slow Encounter
His career development has stalled in recent years through contract problems and extended periods of inactivity.
Once tipped as the future of the British fight scene, he now finds himself trying to realize his potential - maybe in what feels like a final roll of the dice - under recent support.
He started carefully, with neither fighter prepared to overcommit in a calculated early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second appearance at light-heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who utilized a solid defense to narrowly win the more effective periods.
The crowd's patience diminished during frequent holding, with the challenger falling to the floor several times during close exchanges.
Parker finished the stronger, but multiple periods were hard to judge. However, previous titleholder the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor moves on, but with the presence of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Memorial Motivates Local Rivalry Fight
In the secondary fight, Arthur defeated Rea by divided decision in a outstanding Manchester vs Manchester fight to secure the continental championship.
The venue fell silent for a extremely emotional memorial prior to the bout as 10 bells tolled in honor of the city's native Ricky Hatton, who succumbed 46 years old in September.
It was the first major televised fight night in the urban center since the passing of Hatton. As the last bell ended, the silence transitioned to a roar of "there's only one Hatton".
The fighting within the ring matched the sentiment. Arthur was sent to the canvas by a left hook directly to the face in the second round, standing uncertainly to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was injured early, heavy swelling developing under his eye as the pair traded powerful shots.
Rea, 27, connected with strong blows but Arthur, thirty-four, fought fire with fire with effective uppercuts as the action rarely dropped over twelve rounds.
Arthur narrowly won the verdict with judges scorecards of 114-114, 115-113 and clearer margin, but each competitor were persistent and brave, exactly what their idol the legend represented.
