British light heavyweight Joshua Buatsi secured a victory yet underwhelming start to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close 10-round contest at the boxing arena.
But Parker had his moments, delivering effective individual punches in a contest where the styles failed to mesh, with excessive holding disrupting the contest.
The scoring judges scored it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best display but how do champions respond? They prevail," Buatsi said in the ringside as he was greeted with disapproval from the crowd.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Various analysts felt the challenger, 31, should have been awarded the win but the Derbyshire fighter endured the second setback of his 28-bout professional journey.
The Champion Claims Win in Slow Encounter
Buatsi's progress has plateaued in recent years through contract problems and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now is positioned trying to realize his potential - possibly in what feels like a ultimate opportunity - under new promotional backing.
He began cautiously, with the two boxers ready to take risks in a calculated early stages.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after damaging his hand mid-fight, was competing in only his second appearance at the higher weight class.
By the halfway stage, the underdog had kept it close, making life awkward for Buatsi, who utilized a solid defense to edge the more effective rounds.
The spectators' acceptance decreased because of regular grabbing, with Parker falling to the floor multiple occasions during clinches.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, previous titleholder Carl Frampton - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Memorial Fuels Manchester Derby Battle
In the co-main event, Arthur beat Bradley Rea by close verdict in a outstanding local rivalry contest to win the continental championship.
The venue grew hushed for a extremely emotional tribute before the fight as a bell ceremony rang in memory of the city's native Hatton, who died aged 46 in September.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the concluding sound faded, the stillness became a roar of "there's only one Ricky Hatton".
The fighting within the ring equaled the sentiment. Arthur was floored by a significant blow directly to the jaw in the initial stage, standing uncertainly to his position on the referee's count.
But the red-colored shorts of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was damaged soon, heavy swelling 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 stinging uppercuts as the pace rarely dropped over 12 rounds.
The victor edged the result with scoring tallies of 114-114, close margin and 115-112, but each competitor were persistent and courageous, everything their idol Hatton embodied.
