British light-heavyweight Joshua Buatsi secured a victory yet unimpressive beginning to life under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a tight 10-round contest at the boxing arena.
But Parker found success, delivering effective individual punches in a match where the styles didn't complement each other, with excessive holding spoiling the contest.
The officials scored it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my best showing but what do champions do? They win," Buatsi stated in the ring as he was greeted with negative reactions from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Some ringside observers thought the challenger, 31, deserved the win but the Derbyshire fighter suffered the second loss of his 28-match career.
The Champion Secures Victory in Slow Encounter
His career development has stalled in recent times through management issues and extended periods of inactivity.
Earlier forecast as the future of UK boxing, he now is positioned trying to achieve expectations - maybe in what feels like a last chance - under new promotional backing.
He started carefully, with both competitors ready to be aggressive in a calculated initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after suffering a hand injury in the contest, was competing in only his second appearance at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who operated with a tight guard to barely take the more effective periods.
The spectators' acceptance diminished during regular grabbing, with Parker going down various instances during close exchanges.
The underdog finished the stronger, but multiple periods were difficult to score. However, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Motivates All-Manchester Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester contest to win the European light-heavyweight belt.
The venue grew hushed for a profoundly moving homage ahead of the contest as ten bells rang in memory of the city's native Hatton, who succumbed aged 46 in September.
It was the first major televised boxing event in the urban center since Hatton's death. As the concluding sound disappeared, the silence gave way to a shout of "there's just one Ricky Hatton".
The fighting within the ring matched the feeling. The eventual winner was floored by a powerful punch directly to the face in the early round, rising shakily to his position on the eight count.
But the Manchester United-red equipment of Arthur soon advanced again. Across the ring, Rea - in competitive blue - was damaged quickly, significant bruising forming under his face as the fighters landed powerful shots.
Rea, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
The victor edged the result with scoring tallies of even score, narrow lead and wider gap, but each competitor were relentless and brave, exactly what their idol the legend represented.
