British light heavyweight Joshua Buatsi earned a win yet unimpressive debut to life under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a tight ten-round contest at the boxing arena.
But Parker landed significant shots, landing some telling individual punches in a match where the techniques never quite clicked, with constant grabbing spoiling the contest.
Two judges judged it 96-94 in favor 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 commented in the ring as he was faced boos from the spectators.
The Londoner got back to winning after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts felt Parker, 31, should have been awarded the win but the British boxer endured the second defeat of his 28-fight career.
Buatsi Secures Victory in Slow Encounter
His career development has slowed in the past few years through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers ready to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was making just his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to edge the cleaner periods.
The audience's tolerance diminished amid frequent holding, with Parker falling to the floor multiple occasions during grappling.
The underdog closed well, but many rounds were challenging to assess. However, ex-champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the likes of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Homage Fuels Local Rivalry Battle
In the secondary fight, Arthur beat Bradley Rea by close verdict in a excellent local rivalry fight to win the continental championship.
The venue grew hushed for a extremely emotional homage before the fight as 10 bells rang in honor of the city's native Hatton, who died aged 46 in last month.
It was the premier televised match card in the location since the passing of Hatton. As the final chime ended, the stillness transitioned to a shout of "there's just one Ricky Hatton".
The competition within the ring reflected the sentiment. Arthur was sent to the canvas by a significant blow squarely on the face in the second round, getting up unsteadily to his feet on the count of eight.
But the traditional red attire of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was injured early, significant bruising developing under his orbital area as the fighters exchanged hard punches.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the pace seldom decreased over 12 rounds.
Arthur edged the verdict with scoring tallies of even score, 115-113 and wider gap, but both fighters were persistent and full of heart, everything their inspiration Hatton embodied.
