UK light heavyweight Joshua Buatsi made a winning yet underwhelming start to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a judges' verdict in a close ten-round contest at the boxing arena.
But Parker had his moments, landing some telling single shots in a fight where the approaches didn't complement each other, with constant grabbing disrupting the action.
The officials had it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my best showing but what do champions do? They prevail," the victor commented in the ring as he was greeted with disapproval from the audience.
The British fighter bounced back after his maiden career setback - an thrilling contest with his previous opponent in February - to secure a 20th pro success.
Some ringside observers thought Parker, 31, merited the decision but the contender experienced the second defeat of his 28-fight professional journey.
Buatsi Secures Win in Slow Affair
The fighter's advancement has stalled in recent times through management issues and considerable time of lack of fights.
Earlier forecast as the next star of British boxing, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under fresh management.
He started carefully, with the two boxers willing to overcommit in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was making just his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for Buatsi, who utilized a solid defense to narrowly win the more effective rounds.
The audience's tolerance wore thin amid regular grabbing, with the challenger going down various instances during close exchanges.
The underdog closed well, but many rounds were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, giving Buatsi just one round.
The victor advances, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur overcame Rea by divided decision in a outstanding all-Manchester contest to capture the European light-heavyweight championship.
The arena fell silent for a profoundly moving tribute before the fight as 10 bells rang in honor of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell ended, the silence gave way to a chant of "there's just one Ricky Hatton".
The fighting during the bout reflected the emotion. Arthur was sent to the canvas by a powerful punch directly to the face in the early round, standing uncertainly to his position on the eight count.
But the traditional red equipment of the fighter soon advanced again. On the opposite side, the opponent - in rival City blue - was damaged quickly, heavy swelling forming under his eye as the fighters landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the action seldom decreased over twelve rounds.
Arthur barely secured the decision with official scores of draw, narrow lead and clearer margin, but each competitor were relentless and courageous, everything their inspiration the legend embodied.
