British light-heavyweight Joshua Buatsi secured a victory yet unimpressive debut to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a tight ten-round bout at the Manchester venue.
But Parker had his moments, landing some telling individual punches in a contest where the approaches never quite clicked, with frequent clinching marring the fight.
Two judges had it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest performance but what do champions do? They succeed," Buatsi commented in the ringside as he was faced disapproval from the spectators.
The British fighter bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Several boxing experts felt the challenger, 31, should have been awarded the victory but the contender experienced the second defeat of his 28-fight career.
Buatsi Secures Triumph in Uneventful Affair
His career development has plateaued in recent times through contract problems and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors prepared to take risks in a cagey initial rounds.
Parker, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second appearance at the higher weight class.
By the fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who worked behind a solid defense to barely take the better stanzas.
The audience's tolerance diminished amid frequent holding, with Parker falling to the floor several times during close exchanges.
Parker closed well, but several stanzas were challenging to assess. Although, former world champion the boxing analyst - working with the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor advances, but with the presence of hard hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Hatton Tribute Fuels Manchester Derby Battle
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a terrific all-Manchester contest to win the continental championship.
The arena grew hushed for a profoundly moving tribute before the fight as a bell ceremony tolled in honor of Manchester's own Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised fight night in the location since the passing of Hatton. As the concluding sound ended, the silence became a roar of "only one Ricky Hatton".
The action within the ring reflected the sentiment. The eventual winner was knocked down by a left hook flush on the jaw in the initial stage, getting up unsteadily to his feet on the referee's count.
But the red-colored equipment of the fighter soon came forward again. From the other corner, Rea - in rival City blue - was marked up soon, noticeable damage appearing under his eye as the duo landed punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with effective uppercuts as the action seldom decreased over the full distance.
The victor barely secured the result with judges scorecards of even score, narrow lead and wider gap, but both fighters were relentless and brave, all the qualities their inspiration the legend stood for.
