British light-heavyweight Joshua Buatsi made a winning yet underwhelming start to life under recent management with a decision win over Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a tight 10-round fight at the Manchester venue.
But the challenger found success, landing some telling clean blows in a match where the approaches never quite clicked, with excessive holding spoiling the contest.
The officials judged it 96-94 to the winner, with the third a even score.
"It wasn't my greatest performance but what defines champions? They prevail," the victor stated in the ringside as he was greeted with disapproval from the crowd.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts thought Parker, thirty-one, should have been awarded the decision but the Derbyshire fighter experienced the second defeat of his 28-bout professional journey.
Buatsi Secures Win in Dull Match
Buatsi's progress has stalled in recent times through contract problems and considerable time of inactivity.
Earlier forecast as the next star of UK boxing, he now stands trying to achieve expectations - possibly in what seems like a final roll of the dice - under recent support.
He opened tentatively, with neither fighter ready to overcommit in a cagey early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second bout at light heavyweight.
By the halfway stage, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a solid defense to barely take the better rounds.
The spectators' acceptance wore thin amid frequent holding, with Parker slipping to the canvas several times during grappling.
Parker finished the stronger, but several stanzas were hard to judge. However, previous titleholder Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Battle
In the supporting bout, Arthur overcame Rea by close verdict in a outstanding local rivalry contest to win the European light-heavyweight title.
The stadium became quiet for a extremely emotional tribute before the fight as 10 bells sounded in honor of local hero Hatton, who succumbed aged 46 in last month.
It was the first major televised match card in the city since Hatton's passing. As the last bell faded, the stillness gave way to a shout of "only one Ricky Hatton".
The action inside the ropes reflected the sentiment. Arthur 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 shorts of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was damaged quickly, noticeable damage forming under his face as the fighters exchanged hard punches.
The challenger, 27, landed power punches but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity rarely dropped over twelve rounds.
The victor narrowly won the verdict with judges scorecards of even score, narrow lead and clearer margin, but both fighters were determined and brave, exactly what their hero Hatton represented.
