UK light heavyweight Joshua Buatsi secured a victory yet unimpressive start to life under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a split decision in a tight ten-round bout at the boxing arena.
But the challenger found success, delivering effective clean blows in a contest where the approaches failed to mesh, with constant grabbing marring the contest.
The scoring judges scored it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best display but how do champions respond? They prevail," Buatsi commented in the arena as he was greeted with boos 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 secure a 20th pro success.
Various analysts thought the challenger, thirty-one, merited the decision but the Derbyshire fighter suffered the second setback of his 28-match career.
Buatsi Earns Triumph in Uneventful Encounter
The fighter's advancement has plateaued in the past few years through management issues and considerable time of inactivity.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to realize his potential - perhaps in what appears to be a ultimate opportunity - under recent support.
He started carefully, with neither fighter willing to be aggressive in a calculated initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was making just his second fight at the higher weight class.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to barely take the cleaner periods.
The crowd's patience decreased during constant clinching, with the challenger slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. However, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Hatton Tribute Fuels Local Rivalry Contest
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a excellent all-Manchester fight to win the continental belt.
The arena fell silent for a deeply poignant tribute prior to the bout as 10 bells tolled in honor of local hero Hatton, who passed away at age 46 in last month.
It was the premier televised boxing event in the location since Hatton's death. As the final chime ended, the quiet transitioned to a shout of "there's just one Ricky Hatton".
The competition inside the ropes reflected the sentiment. Arthur was sent to the canvas by a left hook flush on the jaw in the early round, getting up unsteadily to his feet on the count of eight.
But the red-colored equipment of Arthur soon pressed ahead again. From the other corner, the opponent - in rival City blue - was damaged early, heavy swelling developing under his eye as the fighters landed punishing blows.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the intensity hardly diminished over twelve rounds.
The victor edged the verdict with scoring tallies of 114-114, 115-113 and clearer margin, but each competitor were determined and brave, all the qualities their hero Hatton embodied.
