British light-heavyweight Joshua Buatsi secured a victory yet disappointing start to life under new promoters with a decision win over Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a majority decision in a competitive 10-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful single shots in a contest where the approaches failed to mesh, with frequent clinching marring the fight.
Two judges had it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my best display but what do champions do? They succeed," 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 last winter - to earn a twentieth professional win.
Various analysts felt Parker, thirty-one, deserved the decision but the contender endured the second setback of his 28-match career.
Buatsi Earns Triumph in Slow Match
His career development has plateaued in the past few years through management issues and long spells of inactivity.
Earlier forecast as the next star of UK boxing, he now is positioned trying to achieve expectations - maybe in what appears to be a final roll of the dice - under recent support.
He opened tentatively, with neither fighter prepared to take risks in a cagey opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second fight at light heavyweight.
By the halfway stage, Parker had stayed in contention, making life awkward for Buatsi, who worked behind a solid defense to barely take the more effective stanzas.
The crowd's patience diminished during frequent holding, with Parker slipping to the canvas multiple occasions during clinches.
Parker closed well, but many rounds were challenging to assess. However, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi advances, but with the likes of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Contest
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester fight to capture the European light heavyweight championship.
The stadium fell silent for a deeply poignant tribute prior to the bout as a bell ceremony sounded in memory of local hero Hatton, who passed away 46 years old in recently.
It was the first major televised match card in the urban center since Hatton's death. As the last bell ended, the stillness transitioned to a shout of "there's just one Ricky Hatton".
The competition during the bout matched the emotion. The eventual winner was floored by a left hook directly to the chin in the early round, rising shakily to his footing on the count of eight.
But the Manchester United-red equipment of the fighter soon came forward again. On the opposite side, Rea - in competitive blue - was damaged soon, noticeable damage appearing under his eye as the fighters exchanged punishing blows.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the intensity rarely dropped over twelve rounds.
Arthur narrowly won the verdict with official scores of draw, 115-113 and clearer margin, but the two athletes were determined and full of heart, exactly what their idol Hatton stood for.
