British light-heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to his career under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a tight 10-round contest at the boxing arena.
But Parker landed significant shots, landing some telling clean blows in a contest where the approaches never quite clicked, with frequent clinching disrupting the action.
Two judges judged it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi said in the arena as he was faced disapproval from the crowd.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in February - to earn a 20th pro success.
Several boxing experts felt the challenger, 31, merited the win but the Derbyshire fighter experienced the second defeat of his 28-bout professional journey.
The Champion Claims Win in Dull Encounter
The fighter's advancement has slowed in recent years through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under recent support.
He began cautiously, with neither fighter prepared to overcommit in a tentative initial rounds.
Parker, whose sole prior loss 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 appearance at light heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who utilized a tight guard to barely take the cleaner periods.
The crowd's patience decreased during constant clinching, with the challenger going down multiple occasions during grappling.
The underdog closed well, but many rounds were difficult to score. Although, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - based on this performance - still seems difficult.
Hatton Memorial Fuels All-Manchester Contest
In the supporting bout, Arthur defeated Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to win the European light heavyweight title.
The venue fell silent for a deeply poignant memorial prior to the bout as 10 bells rang in memory of the city's native Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the last bell faded, the silence transitioned to a roar of "there's only one Hatton".
The action during the bout equaled the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the face in the early round, getting up unsteadily to his footing on the eight count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, Rea - in competitive blue - was marked up quickly, noticeable damage developing under his face as the pair exchanged powerful shots.
The challenger, 27, connected with strong blows but the champion, 34, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
The victor narrowly won the verdict with judges scorecards of draw, narrow lead and wider gap, but both fighters were determined and courageous, exactly what their inspiration the legend represented.
