UK light heavyweight Joshua Buatsi secured a victory yet disappointing start to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a competitive 10-round contest at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a match where the techniques didn't complement each other, with constant grabbing disrupting the action.
The scoring judges scored it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my best showing but what defines champions? They win," Buatsi said in the ringside as he was greeted with disapproval from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Various analysts felt the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter suffered the second defeat of his 28-match career.
The Champion Claims Win in Uneventful Encounter
The fighter's advancement has stalled in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the future of UK boxing, he now stands trying to realize his potential - perhaps in what appears to be a last chance - under new promotional backing.
He started carefully, with neither fighter willing to overcommit in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second bout at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who utilized a tight guard to edge the more effective rounds.
The audience's tolerance wore thin during constant clinching, with Parker going down several times during clinches.
The underdog finished the stronger, but multiple periods were hard to judge. However, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the presence of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Fuels All-Manchester Contest
In the co-main event, Arthur overcame Bradley Rea by divided decision in a terrific Manchester vs Manchester contest to capture the European light heavyweight championship.
The arena became quiet for a deeply poignant memorial ahead of the contest as 10 bells rang in honor of local hero Hatton, who passed away aged 46 in September.
It was the first major televised fight night in the location since Hatton's passing. As the concluding sound ended, the silence gave way to a shout of "there's only one Ricky Hatton".
The competition inside the ropes equaled the feeling. The eventual winner was floored by a left hook squarely on the chin in the second round, getting up unsteadily to his position on the count of eight.
But the red-colored attire of Arthur soon pressed ahead again. On the opposite side, Rea - in rival City blue - was marked up early, noticeable damage forming under his orbital area as the fighters traded hard punches.
Rea, twenty-seven, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
Arthur narrowly won the result with scoring tallies of even score, narrow lead and wider gap, but the two athletes were determined and courageous, everything their hero Hatton stood for.
