UK light heavyweight Joshua Buatsi earned a win yet unimpressive debut to his career 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 majority decision in a tight 10-round bout at the boxing arena.
But the challenger found success, delivering effective individual punches in a fight where the techniques failed to mesh, with excessive holding marring the action.
Two judges scored it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my finest showing but what defines champions? They prevail," the victor said in the ringside as he was met by negative reactions from the spectators.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers thought the challenger, 31, deserved the decision but the Derbyshire fighter endured the second setback of his 28-match professional journey.
Buatsi Secures Triumph in Dull Affair
Buatsi's progress has stalled in recent years through management issues and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now finds himself trying to realize his potential - possibly in what feels like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers prepared to take risks in a tentative early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after breaking his hand in the contest, was competing in only his second appearance at light-heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to narrowly win the better stanzas.
The audience's tolerance decreased because of regular grabbing, with Parker going down multiple occasions during grappling.
Parker ended stronger, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Tribute Fuels Manchester Derby Contest
In the secondary fight, Lyndon Arthur beat Rea by divided decision in a outstanding Manchester vs Manchester fight to win the European light-heavyweight title.
The stadium grew hushed for a extremely emotional memorial ahead of the contest as 10 bells tolled in honor of local hero Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the concluding sound ended, the stillness gave way to a roar of "there's just one Ricky Hatton".
The action within the ring equaled the sentiment. Arthur was knocked down by a left hook flush on the face in the initial stage, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was damaged soon, noticeable damage forming under his face as the duo exchanged punishing blows.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with stinging uppercuts as the action seldom decreased over the full distance.
Arthur narrowly won the decision with official scores of draw, narrow lead and 115-112, but the two athletes were relentless and courageous, exactly what their idol Hatton stood for.
