British light-heavyweight Joshua Buatsi secured a victory yet disappointing debut to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a close 10-round contest at the boxing arena.
But the challenger had his moments, connecting with powerful individual punches in a fight where the techniques never quite clicked, with constant grabbing disrupting the action.
The officials judged it 96-94 for to the winner, with the remaining official a 95-95.
"It wasn't my best display but what do champions do? They win," the victor said in the ring as he was faced negative reactions from the audience.
The British fighter bounced back after his maiden career setback - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Some ringside observers believed the challenger, 31, should have been awarded the win but the contender endured the second defeat of his 28-fight career.
Buatsi Earns Triumph in Uneventful Affair
His career development has plateaued in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to achieve expectations - maybe in what feels like a ultimate opportunity - under recent support.
He opened tentatively, with both competitors prepared to overcommit in a calculated initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was participating in his second appearance at the higher weight class.
By the halfway stage, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the more effective periods.
The crowd's patience decreased during regular grabbing, with the challenger slipping to the canvas various instances during close exchanges.
Parker closed well, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Hatton Memorial Inspires Local Rivalry Battle
In the co-main event, Arthur overcame Bradley Rea by split-decision in a outstanding local rivalry battle to capture the European light-heavyweight belt.
The arena became quiet for a extremely emotional tribute before the fight as a bell ceremony rang in honor of local hero Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised fight night in the city since Hatton's passing. As the last bell faded, the quiet transitioned to a roar of "there's just one Hatton".
The competition within the ring reflected the sentiment. The eventual winner was sent to the canvas by a left hook flush on the jaw in the initial stage, getting up unsteadily to his position on the count of eight.
But the Manchester United-red equipment of Arthur soon advanced again. From the other corner, Rea - in opposing blue - was injured soon, noticeable damage forming under his face as the duo landed powerful shots.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity seldom decreased over twelve rounds.
Arthur barely secured the decision with official scores of 114-114, 115-113 and wider gap, but each competitor were determined and full of heart, exactly what their idol Hatton stood for.
