British light heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to life under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a close ten-round contest at the boxing arena.
But the challenger landed significant shots, delivering effective clean blows in a fight where the approaches never quite clicked, with constant grabbing marring the fight.
The officials had it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi commented in the ring as he was met by negative reactions from the spectators.
The British fighter bounced back after his first professional defeat - an memorable fight with Callum Smith in February - to secure a twentieth professional win.
Various analysts felt the challenger, thirty-one, merited the win but the British boxer experienced the second defeat of his 28-bout career.
The Champion Secures Victory in Uneventful Encounter
The fighter's advancement has slowed in recent years through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - possibly in what feels like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to be aggressive in a calculated early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand in the contest, was participating in his second appearance at light heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who worked behind a tight guard to barely take the better stanzas.
The crowd's patience diminished during frequent holding, with Parker going down various instances during grappling.
The underdog ended stronger, but many rounds were challenging to assess. However, ex-champion Carl Frampton - commentating on Dazn - had it significantly in favor for Parker, awarding Buatsi just one round.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Hatton Tribute Motivates Manchester Derby Contest
In the co-main event, Arthur defeated Bradley Rea by divided decision in a excellent local rivalry battle to capture the continental belt.
The venue fell silent for a extremely emotional homage ahead of the contest as 10 bells sounded in remembrance of the city's native Hatton, who died 46 years old in September.
It was the premier televised boxing event in the city since Hatton's passing. As the final chime ended, the silence gave way to a shout of "there's only one Hatton".
The action inside the ropes matched the sentiment. Arthur was knocked down by a left hook squarely on the jaw in the early round, standing uncertainly to his position on the referee's count.
But the traditional red equipment of the fighter soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was damaged quickly, noticeable damage forming under his orbital area as the duo exchanged hard punches.
The challenger, twenty-seven, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the action seldom decreased over twelve rounds.
The victor edged the verdict with official scores of even score, 115-113 and clearer margin, but the two athletes were relentless and full of heart, everything their hero the legend stood for.
