British light heavyweight Joshua Buatsi earned a win yet unimpressive beginning to his career under fresh promotional backing with a decision win over Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a close 10-round fight at the Manchester venue.
But the challenger landed significant shots, landing some telling individual punches in a fight where the styles never quite clicked, with excessive holding spoiling the fight.
The officials had it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but what defines champions? They prevail," the victor said in the ringside as he was met by boos from the crowd.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to earn a twentieth professional win.
Various analysts felt the challenger, 31, should have been awarded the decision but the British boxer experienced the second setback of his 28-bout professional journey.
The Champion Secures Victory in Slow Match
The fighter's advancement has plateaued in recent years through promotional disputes and long spells of lack of fights.
Previously predicted as the next star of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He started carefully, with the two boxers willing to be aggressive in a calculated early stages.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second bout at the higher weight class.
By the halfway stage, the underdog had kept it close, causing problems for the favorite, who operated with a tight guard to edge the cleaner periods.
The crowd's patience decreased because of regular grabbing, with the challenger going down multiple occasions during grappling.
Parker closed well, but several stanzas were challenging to assess. Although, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Fuels Local Rivalry Battle
In the secondary fight, Arthur defeated Rea by divided decision in a excellent all-Manchester fight to capture the continental championship.
The venue grew hushed for a extremely emotional tribute ahead of the contest as 10 bells sounded in honor of local hero Hatton, who succumbed at age 46 in recently.
It was the first major televised boxing event in the city since the passing of Hatton. As the concluding sound disappeared, the silence gave way to a roar of "only one Hatton".
The action during the bout reflected the emotion. The eventual winner was knocked down by a significant blow flush on the jaw in the initial stage, rising shakily to his position on the eight count.
But the traditional red attire of the fighter soon advanced again. From the other corner, Rea - in competitive blue - was marked up soon, significant bruising developing under his face as the pair traded punishing blows.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the intensity hardly diminished over 12 rounds.
Arthur barely secured the verdict with official scores of draw, 115-113 and wider gap, but the two athletes were relentless and full of heart, all the qualities their idol Hatton embodied.
