UK light-heavyweight Joshua Buatsi made a winning yet underwhelming debut to his career under new promoters with a decision win over Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a tight 10-round bout at the boxing arena.
But the challenger landed significant shots, landing some telling individual punches in a match where the approaches never quite clicked, with constant grabbing disrupting the fight.
The officials had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest display but how do champions respond? They succeed," Buatsi stated in the ring as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in February - to earn a 20th career victory.
Various analysts believed the challenger, thirty-one, should have been awarded the win but the British boxer endured the second loss of his 28-match career.
Buatsi Claims Victory in Dull Match
His career development has slowed in recent years through contract problems and long spells of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a last chance - under fresh management.
He began cautiously, with neither fighter willing to overcommit in a calculated opening few rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after damaging his hand in the contest, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who worked behind a tight guard to barely take the better stanzas.
The spectators' acceptance diminished because of regular grabbing, with the challenger slipping to the canvas various instances during clinches.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion the boxing analyst - working with Dazn - had it particularly wide for Parker, giving Buatsi just a single round.
The victor advances, but with the likes of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Hatton Tribute Motivates Local Rivalry Battle
In the co-main event, Arthur overcame Bradley Rea by divided decision in a terrific all-Manchester contest to win the European light-heavyweight belt.
The venue became quiet for a deeply poignant tribute prior to the bout as 10 bells rang in honor of local hero Hatton, who died at age 46 in September.
It was the first major televised boxing event in the urban center since Hatton's passing. As the final chime disappeared, the stillness gave way to a roar of "only one Hatton".
The action during the bout equaled the feeling. Arthur was sent to the canvas by a powerful punch flush on the jaw in the early round, standing uncertainly to his footing on the eight count.
But the red-colored equipment of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was marked up early, heavy swelling developing under his orbital area as the duo exchanged hard punches.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with effective uppercuts as the action hardly diminished over the full distance.
Arthur edged the verdict with official scores of draw, 115-113 and clearer margin, but both fighters were persistent and brave, everything their hero Hatton stood for.
