UK light-heavyweight Joshua Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a decision win over Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a split decision in a tight ten-round contest at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a match where the techniques never quite clicked, with constant grabbing disrupting the contest.
The officials had it 96-94 for to the winner, with the remaining official a even score.
"It wasn't my finest showing but what do champions do? They prevail," the victor commented in the ringside as he was faced boos from the audience.
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 pro success.
Several boxing experts believed the challenger, 31, deserved the win but the Derbyshire fighter endured the second setback of his 28-match career.
Buatsi Earns Triumph in Uneventful Encounter
The fighter's advancement has slowed in recent times through contract problems and extended periods of inactivity.
Previously predicted as the rising talent of UK boxing, he now finds himself trying to achieve expectations - maybe in what feels like a last chance - under fresh management.
He began cautiously, with both competitors ready to take risks in a tentative opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had kept it close, making life awkward for Buatsi, who utilized a protective stance to edge the better stanzas.
The crowd's patience diminished during frequent holding, with the challenger going down several times during grappling.
Parker finished the stronger, but many rounds were challenging to assess. However, former world champion the boxing analyst - working with Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the caliber of hard hitter Benavidez, and Russian star Bivol leading the category, the road to world glory - based on this performance - still looks steep.
Hatton Homage Fuels Local Rivalry Contest
In the supporting bout, Arthur defeated Rea by divided decision in a terrific Manchester vs Manchester contest to win the European light heavyweight championship.
The venue fell silent for a profoundly moving homage ahead of the contest as a bell ceremony rang in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the first major televised fight night in the city since Hatton's death. As the concluding sound faded, the stillness gave way to a shout of "there's only one Hatton".
The action within the ring matched the feeling. The eventual winner was floored by a significant blow flush on the chin in the initial stage, getting up unsteadily to his feet on the count of eight.
But the traditional red shorts of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was injured soon, significant bruising appearing under his orbital area as the duo landed hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with stinging uppercuts as the intensity rarely dropped over twelve rounds.
Arthur barely secured the result with scoring tallies of even score, 115-113 and clearer margin, but each competitor were determined and brave, all the qualities their inspiration Hatton embodied.
