UK light-heavyweight Joshua Buatsi made a winning yet unimpressive debut to life under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a split decision in a competitive 10-round contest at the Co-op Live Arena.
But Parker found success, landing some telling clean blows in a match where the techniques never quite clicked, with frequent clinching marring the fight.
Two judges judged it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my best display but how do champions respond? They succeed," the victor said in the ringside as he was faced boos from the audience.
The British fighter bounced back after his initial pro loss - an thrilling contest with Callum Smith in February - to claim a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the decision but the British boxer experienced the second setback of his 28-match career.
The Champion Secures Triumph in Uneventful Match
Buatsi's progress has stalled in recent years through contract problems and long spells of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to realize his potential - perhaps in what appears to be a last chance - under fresh management.
He began cautiously, with neither fighter ready to be aggressive in a calculated early stages.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at light heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for the favorite, who utilized a tight guard to edge the more effective rounds.
The spectators' acceptance diminished because of constant clinching, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were challenging to assess. However, ex-champion Carl Frampton - commentating on Dazn - had it significantly in favor for the challenger, giving Buatsi just one round.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Hatton Homage Inspires All-Manchester Contest
In the co-main event, Arthur defeated Rea by split-decision in a excellent Manchester vs Manchester contest to capture the European light-heavyweight championship.
The arena fell silent for a deeply poignant tribute before the fight as ten bells rang in honor of Manchester's own Ricky Hatton, who passed away aged 46 in recently.
It was the premier televised fight night in the city since Hatton's death. As the concluding sound faded, the silence became a chant of "there's just one Hatton".
The fighting inside the ropes reflected the emotion. Arthur was floored by a powerful punch squarely on the chin in the early round, rising shakily to his position on the eight count.
But the Manchester United-red shorts of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was injured soon, noticeable damage appearing under his face as the fighters exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the pace seldom decreased over the full distance.
Arthur narrowly won the verdict with judges scorecards of 114-114, narrow lead and 115-112, but both fighters were relentless and courageous, everything their inspiration Hatton represented.
