British light heavyweight Joshua Buatsi earned a win yet underwhelming beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a tight 10-round bout at the Manchester venue.
But Parker found success, landing some telling individual punches in a match where the approaches didn't complement each other, with frequent clinching spoiling the action.
The scoring judges scored it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi said in the ringside as he was greeted with boos from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers thought the challenger, 31, deserved the victory but the contender suffered the second loss of his 28-bout career.
The Champion Earns Victory in Slow Match
The fighter's advancement has slowed in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the rising talent of UK boxing, he now stands trying to achieve expectations - maybe in what seems like a ultimate opportunity - under recent support.
He opened tentatively, with neither fighter prepared to take risks in a calculated early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second fight at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, causing problems for the favorite, who worked behind a tight guard to narrowly win the cleaner stanzas.
The audience's tolerance decreased because of constant clinching, with Parker slipping to the canvas multiple occasions during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. Nevertheless, former world champion Carl Frampton - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just a single round.
The victor moves on, but with the likes of heavy hitter Benavidez, and Russian star Bivol leading the category, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a excellent all-Manchester battle to capture the European light heavyweight title.
The venue fell silent for a deeply poignant memorial ahead of the contest as a bell ceremony sounded in remembrance of local hero Ricky Hatton, who passed away aged 46 in recently.
It was the first major televised boxing event in the location since the passing of Hatton. As the final chime ended, the silence transitioned to a roar of "there's just one Hatton".
The fighting during the bout matched the sentiment. The eventual winner was sent to the canvas by a left hook directly to the chin in the initial stage, rising shakily to his position on the count of eight.
But the red-colored shorts of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was injured quickly, heavy swelling developing under his face as the fighters exchanged hard punches.
Rea, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with effective uppercuts as the intensity rarely dropped over the full distance.
The victor narrowly won the decision with scoring tallies of draw, narrow lead and 115-112, but both fighters were relentless and full of heart, everything their inspiration Hatton embodied.
