British light heavyweight Joshua Buatsi secured a victory yet unimpressive beginning to his career under recent management with a points victory over Parker in Manchester.
The Olympic medal winner's activity level likely gained him a split decision in a tight ten-round contest at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful clean blows in a match where the techniques never quite clicked, with excessive holding spoiling the fight.
The scoring judges judged it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my finest performance but what defines champions? They succeed," the victor said in the ringside as he was greeted with disapproval from the crowd.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in February - to earn a 20th career victory.
Some ringside observers believed the challenger, 31, should have been awarded the victory but the Derbyshire fighter suffered the second loss of his 28-match career.
Buatsi Claims Victory in Uneventful Encounter
Buatsi's progress has stalled in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now finds himself trying to realize his potential - possibly in what appears to be a last chance - under recent support.
He started carefully, with both competitors prepared to take risks in a calculated early stages.
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 mid-fight, was making just his second bout at the higher weight class.
By the halfway stage, the underdog had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to edge the better rounds.
The spectators' acceptance wore thin during frequent holding, with Parker going down various instances during grappling.
Parker ended stronger, but many rounds were difficult to score. Although, former world champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Memorial Inspires All-Manchester Fight
In the secondary fight, Lyndon Arthur beat Rea by divided decision in a excellent Manchester vs Manchester fight to capture the European light-heavyweight title.
The arena fell silent for a profoundly moving homage before the fight as a bell ceremony sounded in remembrance of Manchester's own Hatton, who succumbed at age 46 in September.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound ended, the silence became a shout of "only one Hatton".
The action during the bout equaled the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the face in the initial stage, standing uncertainly to his position on the referee's count.
But the traditional red equipment of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was injured quickly, heavy swelling forming under his face as the fighters traded punishing blows.
Rea, twenty-seven, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the intensity hardly diminished over twelve rounds.
The victor narrowly won the verdict with official scores of 114-114, narrow lead and clearer margin, but each competitor were persistent and brave, all the qualities their idol the legend represented.
