UK light-heavyweight Joshua Buatsi secured a victory yet disappointing beginning to his career under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a competitive ten-round contest at the Manchester venue.
But Parker had his moments, landing some telling clean blows in a contest where the styles never quite clicked, with constant grabbing marring the contest.
Two judges scored it 96-94 in favor to the winner, with the remaining official a even score.
"It wasn't my best performance but how do champions respond? They prevail," Buatsi commented in the ringside as he was greeted with boos from the crowd.
The Londoner got back to winning after his maiden career setback - an thrilling contest with Callum Smith in February - to claim a twentieth professional win.
Various analysts believed the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter suffered the second setback of his 28-fight professional journey.
Buatsi Claims Win in Uneventful Encounter
Buatsi's progress has stalled in recent times through management issues and considerable time of lack of fights.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter ready to overcommit in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against his former opponent in two years ago after damaging his hand during the bout, 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 worked behind a tight guard to narrowly win the more effective stanzas.
The crowd's patience diminished because of frequent holding, with Parker going down several times during close exchanges.
Parker finished the stronger, but many rounds were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Memorial Motivates Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Rea by split-decision in a outstanding local rivalry battle to win the continental title.
The arena became quiet for a profoundly moving memorial prior to the bout as 10 bells rang in honor of Manchester's own Ricky Hatton, who passed away 46 years old in September.
It was the premier televised match card in the city since the passing of Hatton. As the final chime ended, the quiet gave way to a chant of "there's just one Hatton".
The action during the bout reflected the emotion. Arthur was floored by a powerful punch directly to the chin in the early round, getting up unsteadily to his feet on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, the opponent - in rival City blue - was injured quickly, heavy swelling appearing under his orbital area as the duo exchanged hard punches.
Rea, 27, connected with strong blows but Arthur, 34, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
Arthur edged the verdict with judges scorecards of even score, 115-113 and wider gap, but each competitor were relentless and brave, all the qualities their idol the legend embodied.
