British light-heavyweight Joshua Buatsi earned a win yet underwhelming beginning to life under recent management with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a tight ten-round bout at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful individual punches in a match where the styles failed to mesh, with frequent clinching marring the fight.
The officials scored it 96-94 for to the winner, with the remaining official a 95-95.
"It wasn't my greatest showing but how do champions respond? They succeed," the victor stated in the arena as he was met by negative reactions from the spectators.
The Londoner got back to winning after his initial pro loss - an thrilling contest with Callum Smith in last winter - to earn a 20th career victory.
Some ringside observers felt the challenger, 31, should have been awarded the victory but the contender endured the second defeat of his 28-bout career.
The Champion Claims Victory in Uneventful Encounter
Buatsi's progress has plateaued in recent times through management issues and considerable time of lack of fights.
Earlier forecast as the future of UK boxing, he now stands trying to fulfil that early promise - maybe in what appears to be a last chance - under fresh management.
He started carefully, with neither fighter willing to take risks in a cagey opening few rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after damaging his hand mid-fight, was competing in only his second fight at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who utilized a solid defense to narrowly win the better stanzas.
The spectators' acceptance diminished amid regular grabbing, with the challenger slipping to the canvas various instances during grappling.
The underdog finished the stronger, but many rounds were hard to judge. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just one round.
The victor advances, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Hatton Tribute Fuels Local Rivalry Contest
In the supporting bout, Arthur overcame Rea by split-decision in a outstanding local rivalry fight to secure the European light-heavyweight belt.
The venue fell silent for a extremely emotional homage before the fight as 10 bells sounded in remembrance of Manchester's own Hatton, who succumbed aged 46 in September.
It was the first major televised match card in the city since Hatton's death. As the final chime faded, the quiet transitioned to a chant of "only one Ricky Hatton".
The action during the bout equaled the emotion. Arthur was floored by a left hook directly to the face in the second round, standing uncertainly to his position on the referee's count.
But the traditional red attire of Arthur soon advanced again. On the opposite side, Rea - in rival City blue - was injured soon, significant bruising appearing under his face as the pair traded powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the intensity seldom decreased over the full distance.
The victor narrowly won the result with scoring tallies of draw, narrow lead and 115-112, but the two athletes were persistent and brave, exactly what their inspiration Hatton embodied.
