British light-heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to life under new promoters with a points victory over Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a majority decision in a tight 10-round bout at the boxing arena.
But Parker had his moments, landing some telling single shots in a fight where the techniques failed to mesh, with constant grabbing spoiling the action.
The officials judged it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my finest performance but how do champions respond? They prevail," the victor commented in the ringside as he was greeted with disapproval from the crowd.
The British fighter returned to winning ways after his maiden career setback - an epic battle with Callum Smith in February - to claim a twentieth professional win.
Several boxing experts felt Parker, 31, merited the win but the contender suffered the second setback of his 28-fight career.
Buatsi Claims Victory in Dull Affair
The fighter's advancement has slowed in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under fresh management.
He began cautiously, with neither fighter ready to take risks in a cagey early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second appearance at the higher weight class.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who utilized a tight guard to narrowly win the more effective stanzas.
The audience's tolerance wore thin because of regular grabbing, with Parker slipping to the canvas various instances during grappling.
The underdog finished the stronger, but multiple periods were challenging to assess. Nevertheless, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi advances, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - judging by this showing - still seems difficult.
Hatton Homage Fuels All-Manchester Contest
In the supporting bout, Arthur beat Bradley Rea by split-decision in a outstanding Manchester vs Manchester fight to win the continental championship.
The stadium grew hushed for a extremely emotional homage ahead of the contest as 10 bells tolled in memory of the city's native Ricky Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast match card in the location since Hatton's death. As the final chime faded, the stillness became a roar of "there's only one Ricky Hatton".
The fighting within the ring matched the emotion. The eventual winner was knocked down by a left hook directly to the face in the early round, rising shakily to his feet on the count of eight.
But the red-colored equipment of Arthur soon pressed ahead again. Across the ring, Rea - in competitive blue - was injured soon, heavy swelling appearing under his face as the pair exchanged punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace seldom decreased over twelve rounds.
Arthur edged the verdict with scoring tallies of even score, close margin and clearer margin, but the two athletes were determined and brave, exactly what their hero Hatton stood for.
