British light heavyweight Joshua Buatsi made a winning yet unimpressive beginning to life under new promoters with a unanimous decision over Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a tight 10-round contest at the Manchester venue.
But the challenger landed significant shots, connecting with powerful individual punches in a match where the styles never quite clicked, with excessive holding spoiling the fight.
The officials judged it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my best showing but how do champions respond? They win," Buatsi commented in the ringside as he was faced boos 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.
Various analysts felt Parker, thirty-one, merited the decision but the contender suffered the second setback of his 28-match career.
Buatsi Claims Triumph in Slow Encounter
The fighter's advancement has slowed in recent times through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of UK boxing, he now stands trying to fulfil that early promise - possibly in what seems like a ultimate opportunity - under new promotional backing.
He started carefully, with both competitors willing to take risks in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand during the bout, was participating in his second appearance at light heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who operated with a protective stance to barely take the cleaner periods.
The spectators' acceptance wore thin because of regular grabbing, with the challenger going down multiple occasions during clinches.
Parker finished the stronger, but several stanzas were challenging to assess. Although, former world champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Battle
In the co-main event, Arthur beat Bradley Rea by close verdict in a outstanding local rivalry fight to capture the European light-heavyweight belt.
The arena fell silent for a deeply poignant homage ahead of the contest as a bell ceremony tolled in remembrance of Manchester's own Hatton, who succumbed at age 46 in September.
It was the first major televised match card in the urban center since the passing of Hatton. As the concluding sound ended, the stillness became a shout of "there's only one Ricky Hatton".
The competition during the bout equaled the feeling. Arthur was floored by a left hook squarely on the face in the second round, rising shakily to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up early, noticeable damage developing under his orbital area as the duo exchanged powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over twelve rounds.
The victor edged the verdict with official scores of draw, narrow lead and 115-112, but each competitor were relentless and brave, all the qualities their idol Hatton represented.
