British light-heavyweight Joshua Buatsi secured a victory yet underwhelming start to his career under recent management with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a judges' verdict in a tight 10-round bout at the Manchester venue.
But the challenger found success, landing some telling single shots in a match where the techniques failed to mesh, with excessive holding disrupting the action.
The officials judged it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest display but how do champions respond? They win," Buatsi stated in the ring as he was faced disapproval from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with Callum Smith in February - to earn a 20th career victory.
Various analysts felt the challenger, thirty-one, deserved the win but the British boxer experienced the second defeat of his 28-match career.
Buatsi Secures Victory in Slow Match
His career development has stalled in recent years through management issues and considerable time of lack of fights.
Earlier forecast as the next star of British boxing, he now finds himself trying to realize his potential - possibly in what appears to be a ultimate opportunity - under fresh management.
He started carefully, with both competitors willing to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was making just his second appearance at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a tight guard to barely take the more effective stanzas.
The audience's tolerance decreased amid regular grabbing, with Parker falling to the floor several times during grappling.
Parker finished the stronger, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just one round.
Buatsi progresses, but with the presence of power puncher Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Tribute Motivates All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester fight to secure the European light-heavyweight championship.
The arena became quiet for a extremely emotional homage before the fight as ten bells rang in remembrance of Manchester's own Ricky Hatton, who succumbed at age 46 in recently.
It was the first major televised match card in the location since Hatton's passing. As the last bell disappeared, the quiet transitioned to a chant of "there's only one Ricky Hatton".
The action during the bout equaled the emotion. The eventual winner was floored by a left hook flush on the face in the second round, rising shakily to his feet on the count of eight.
But the red-colored attire of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was damaged soon, heavy swelling developing under his eye as the fighters landed powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity rarely dropped over the full distance.
Arthur barely secured the verdict with scoring tallies of draw, narrow lead and 115-112, but the two athletes were persistent and courageous, everything their inspiration Hatton represented.
