UK light heavyweight Joshua Buatsi earned a win yet unimpressive start to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a close ten-round bout at the boxing arena.
But the challenger landed significant shots, connecting with powerful individual punches in a contest where the techniques didn't complement each other, with constant grabbing disrupting the fight.
Two judges scored it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my greatest display but how do champions respond? They succeed," Buatsi said in the ring as he was faced disapproval from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with his previous opponent in February - to earn a 20th career victory.
Various analysts thought the challenger, thirty-one, deserved the win but the British boxer experienced the second setback of his 28-fight career.
Buatsi Claims Win in Uneventful Affair
The fighter's advancement has slowed in recent times through management issues and extended periods of inactivity.
Previously predicted as the next star of UK boxing, he now stands trying to achieve expectations - maybe in what appears to be a final roll of the dice - under recent support.
He opened tentatively, with neither fighter ready to overcommit in a tentative opening few rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was competing in only his second fight at the higher weight class.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who worked behind a protective stance to narrowly win the better rounds.
The spectators' acceptance diminished amid frequent holding, with Parker going down various instances during close exchanges.
Parker closed well, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - working with the broadcast network - had it strongly leaning for Parker, giving Buatsi just one round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Tribute Inspires Local Rivalry Battle
In the secondary fight, Arthur defeated Rea by split-decision in a excellent all-Manchester contest to capture the European light-heavyweight belt.
The stadium fell silent for a extremely emotional homage ahead of the contest as a bell ceremony rang in honor of Manchester's own Hatton, who succumbed aged 46 in September.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound faded, the silence became a roar of "there's just one Ricky Hatton".
The fighting inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a powerful punch squarely on the chin in the second round, getting up unsteadily to his feet on the referee's count.
But the Manchester United-red attire of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was marked up soon, heavy swelling forming under his eye as the pair traded hard punches.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the action rarely dropped over the full distance.
The victor edged the result with scoring tallies of even score, narrow lead and clearer margin, but each competitor were determined and full of heart, exactly what their idol Hatton represented.
