British light-heavyweight Joshua Buatsi earned a win yet unimpressive start to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a judges' verdict in a tight ten-round contest at the Co-op Live Arena.
But the challenger found success, landing some telling single shots in a contest where the approaches failed to mesh, with excessive holding spoiling the fight.
The officials scored it 96-94 to the winner, with the third a even score.
"It wasn't my greatest showing but how do champions respond? They succeed," the victor stated in the ringside as he was greeted with boos from the crowd.
The British fighter got back to winning after his initial pro loss - an memorable fight with Callum Smith in February - to claim a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the win but the contender endured the second loss of his 28-bout professional journey.
Buatsi Claims Win in Uneventful Affair
Buatsi's progress has stalled in recent years through contract problems and long spells of lack of fights.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to fulfil that early promise - maybe in what appears to be a last chance - under new promotional backing.
He began cautiously, with the two boxers willing to take risks in a tentative early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who operated with a protective stance to edge the better periods.
The spectators' acceptance decreased during frequent holding, with Parker slipping to the canvas several times during close exchanges.
Parker closed well, but several stanzas were hard to judge. However, ex-champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor advances, but with the caliber of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Hatton Memorial Motivates All-Manchester Battle
In the secondary fight, Lyndon Arthur overcame Bradley Rea by divided decision in a outstanding local rivalry battle to secure the European light heavyweight belt.
The stadium became quiet for a deeply poignant memorial ahead of the contest as a bell ceremony tolled in memory of the city's native Ricky Hatton, who succumbed 46 years old in last month.
It was the first major televised match card in the location since the passing of Hatton. As the concluding sound disappeared, the silence transitioned to a shout of "there's only one Ricky Hatton".
The action during the bout reflected the emotion. The eventual winner was sent to the canvas by a left hook squarely on the chin in the early round, standing uncertainly to his footing on the referee's count.
But the red-colored equipment of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was marked up early, significant bruising developing under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the action rarely dropped over 12 rounds.
Arthur edged the decision with judges scorecards of even score, 115-113 and wider gap, but the two athletes were persistent and full of heart, all the qualities their inspiration the legend embodied.
