British light-heavyweight Joshua Buatsi made a winning yet underwhelming debut to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a majority decision in a close 10-round bout at the boxing arena.
But Parker landed significant shots, delivering effective individual punches in a match where the approaches failed to mesh, with frequent clinching spoiling the action.
The officials scored it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi stated in the ringside as he was faced negative reactions from the crowd.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a 20th pro success.
Several boxing experts thought the challenger, thirty-one, should have been awarded the win but the British boxer suffered the second setback of his 28-fight professional journey.
Buatsi Earns Victory in Uneventful Encounter
His career development has stalled in the past few years through promotional disputes and extended periods of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to achieve expectations - maybe in what feels like a ultimate opportunity - under recent support.
He started carefully, with neither fighter ready to overcommit in a tentative opening few rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was participating in his second bout at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for the favorite, who utilized a solid defense to barely take the more effective stanzas.
The audience's tolerance wore thin during frequent holding, with the challenger going down various instances during close exchanges.
The underdog closed well, but many rounds were hard to judge. Although, previous titleholder Carl Frampton - commentating on the broadcast network - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor moves on, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the co-main event, Arthur beat Bradley Rea by split-decision in a excellent local rivalry battle to capture the European light-heavyweight title.
The stadium grew hushed for a deeply poignant tribute prior to the bout as a bell ceremony rang in remembrance of Manchester's own Ricky Hatton, who died 46 years old in recently.
It was the first major televised match card in the urban center since Hatton's death. As the concluding sound ended, the stillness gave way to a shout of "there's just one Hatton".
The action during the bout equaled the feeling. The eventual winner was sent to the canvas by a left hook flush on the chin in the second round, standing uncertainly to his feet on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was injured soon, heavy swelling appearing under his eye as the duo landed hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the action seldom decreased over 12 rounds.
The victor edged the verdict with judges scorecards of draw, narrow lead and 115-112, but the two athletes were persistent and brave, everything their hero the legend represented.
