British light heavyweight Joshua Buatsi made a winning yet underwhelming debut to his career under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a tight 10-round contest at the Co-op Live Arena.
But Parker had his moments, connecting with powerful individual punches in a match where the techniques never quite clicked, with frequent clinching disrupting the action.
Two judges scored it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but what defines champions? They succeed," the victor stated in the ringside as he was faced boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Several boxing experts thought Parker, thirty-one, deserved the win but the Derbyshire fighter suffered the second setback of his 28-fight career.
Buatsi Earns Triumph in Dull Match
Buatsi's progress has plateaued in the past few years through promotional disputes and long spells of inactivity.
Previously predicted as the next star of British boxing, he now is positioned trying to realize his potential - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with both competitors willing to be aggressive in a calculated opening few rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was participating in his second appearance at light-heavyweight.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who operated with a solid defense to barely take the cleaner stanzas.
The spectators' acceptance wore thin during frequent holding, with the challenger falling to the floor various instances during clinches.
The underdog closed well, but multiple periods were hard to judge. However, former world champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Memorial Inspires All-Manchester Fight
In the co-main event, Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester battle to win the European light heavyweight championship.
The venue became quiet for a profoundly moving homage before the fight as a bell ceremony tolled in remembrance of Manchester's own Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast match card in the city since Hatton's death. As the last bell ended, the stillness gave way to a shout of "there's only one Ricky Hatton".
The fighting inside the ropes matched the emotion. Arthur was knocked down by a significant blow flush on the face in the initial stage, standing uncertainly to his footing on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up soon, heavy swelling forming under his face as the pair exchanged hard punches.
The challenger, 27, connected with strong blows but the champion, thirty-four, fought fire with fire with stinging uppercuts as the pace rarely dropped over twelve rounds.
The victor edged the verdict with judges scorecards of draw, 115-113 and 115-112, but each competitor were relentless and courageous, everything their idol the legend embodied.
