British light heavyweight Joshua Buatsi secured a victory yet disappointing debut to life under new promoters with a points victory over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a competitive ten-round contest at the boxing arena.
But the challenger landed significant shots, landing some telling clean blows in a fight where the styles failed to mesh, with excessive holding disrupting the contest.
Two judges scored it 96-94 for to the winner, with the third a even score.
"It wasn't my greatest performance but what defines champions? They succeed," the victor stated in the ring as he was greeted with boos from the spectators.
The Londoner bounced back after his maiden career setback - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, merited the decision but the British boxer experienced the second setback of his 28-bout professional journey.
Buatsi Secures Victory in Dull Affair
The fighter's advancement has plateaued in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of British boxing, he now is positioned trying to achieve expectations - possibly in what appears to be a last chance - under fresh management.
He started carefully, with both competitors willing to be aggressive in a cagey early stages.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second bout at light-heavyweight.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who utilized a tight guard to edge the cleaner periods.
The audience's tolerance wore thin during regular grabbing, with Parker going down various instances during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. Nevertheless, ex-champion Carl Frampton - commentating on Dazn - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the caliber of hard hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Hatton Tribute Fuels Manchester Derby Contest
In the co-main event, Lyndon Arthur overcame Bradley Rea by divided decision in a excellent local rivalry battle to win the European light-heavyweight championship.
The venue grew hushed for a profoundly moving homage before the fight as ten bells sounded in honor of local hero Hatton, who died aged 46 in last month.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the final chime disappeared, the stillness became a chant of "there's just one Ricky Hatton".
The action during the bout equaled the emotion. Arthur was sent to the canvas by a left hook directly to the chin in the second round, getting up unsteadily to his feet on the referee's count.
But the traditional red shorts of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was damaged quickly, noticeable damage forming under his orbital area as the fighters exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity rarely dropped over 12 rounds.
The victor narrowly won the verdict with official scores of even score, 115-113 and clearer margin, but the two athletes were relentless and full of heart, everything their idol the legend stood for.
