British light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under new promoters with a unanimous decision over Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight ten-round bout at the Co-op Live Arena.
But Parker landed significant shots, landing some telling individual punches in a fight where the approaches didn't complement each other, with frequent clinching marring the contest.
The scoring judges judged it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my best showing but what defines champions? They win," the victor stated in the ringside as he was faced negative reactions from the audience.
The British fighter bounced back after his first professional defeat - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers felt Parker, thirty-one, deserved the decision but the British boxer suffered the second setback of his 28-bout professional journey.
The Champion Claims Win in Uneventful Affair
Buatsi's progress has stalled in recent times through management issues and considerable time of inactivity.
Earlier forecast as the rising talent of British boxing, he now is positioned trying to realize his potential - maybe in what seems like a last chance - under fresh management.
He began cautiously, with neither fighter prepared to be aggressive in a cagey opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after damaging his hand in the contest, was making just his second bout at the higher weight class.
By the fight's midpoint, Parker had kept it close, making life awkward for the favorite, who operated with a protective stance to narrowly win the better periods.
The audience's tolerance wore thin because of regular grabbing, with the challenger slipping to the canvas multiple occasions during grappling.
Parker ended stronger, but multiple periods were challenging to assess. Although, ex-champion the boxing analyst - working with the broadcast network - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the caliber of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Homage Fuels All-Manchester Fight
In the supporting bout, Arthur beat Rea by divided decision in a excellent local rivalry fight to capture the continental championship.
The arena became quiet for a deeply poignant memorial ahead of the contest as ten bells rang in memory of Manchester's own Hatton, who succumbed 46 years old in last month.
It was the first major televised boxing event in the city since Hatton's death. As the last bell disappeared, the stillness became a shout of "there's just one Hatton".
The fighting inside the ropes matched the feeling. The eventual winner was floored by a left hook directly to the face in the early round, rising shakily to his position on the referee's count.
But the traditional red equipment of the fighter soon pressed ahead again. On the opposite side, Rea - in rival City blue - was marked up early, noticeable damage forming under his eye as the pair exchanged powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with effective uppercuts as the action hardly diminished over 12 rounds.
Arthur edged the result with official scores of even score, close margin and clearer margin, but each competitor were persistent and brave, everything their idol Hatton stood for.
