UK light heavyweight Joshua Buatsi made a winning yet unimpressive start to life under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a tight ten-round contest at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful single shots in a match where the approaches didn't complement each other, with frequent clinching disrupting the fight.
Two judges scored it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best showing but what defines champions? They succeed," Buatsi commented in the ring as he was greeted with boos from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with his previous opponent in February - to secure a 20th career victory.
Several boxing experts believed the challenger, thirty-one, deserved the victory but the Derbyshire fighter endured the second defeat of his 28-match professional journey.
Buatsi Secures Win in Dull Encounter
His career development has plateaued in recent years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to realize his potential - maybe in what feels like a ultimate opportunity - under recent support.
He opened tentatively, with neither fighter prepared to overcommit in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was competing in only his second bout at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who operated with a protective stance to barely take the better rounds.
The audience's tolerance diminished amid frequent holding, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were challenging to assess. However, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi progresses, but with the caliber of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the path to championship success - based on this performance - still seems difficult.
Hatton Homage Fuels Manchester Derby Fight
In the supporting bout, Arthur beat Rea by split-decision in a excellent all-Manchester fight to win the continental championship.
The arena grew hushed for a profoundly moving tribute prior to the bout as ten bells tolled in remembrance of the city's native Hatton, who died 46 years old in last month.
It was the first major televised match card in the urban center since Hatton's death. As the final chime ended, the silence became a roar of "there's just one Hatton".
The competition inside the ropes matched the feeling. Arthur was floored by a significant blow directly to the chin in the early round, getting up unsteadily to his position on the eight count.
But the traditional red shorts of Arthur soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged early, noticeable damage appearing under his eye as the duo traded powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity seldom decreased over 12 rounds.
The victor edged the result with scoring tallies of 114-114, close margin and 115-112, but both fighters were relentless and brave, all the qualities their inspiration Hatton represented.
