British light heavyweight Joshua Buatsi secured a victory yet underwhelming beginning to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a split decision in a tight 10-round fight at the Co-op Live Arena.
But the challenger found success, connecting with powerful single shots in a fight where the approaches failed to mesh, with frequent clinching marring the action.
The scoring judges scored it 96-94 for to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest display but what defines champions? They prevail," Buatsi stated in the ring as he was faced negative reactions from the crowd.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts believed Parker, 31, deserved the decision but the Derbyshire fighter endured the second defeat of his 28-match career.
Buatsi Earns Win in Uneventful Encounter
His career development has plateaued in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the next star of UK boxing, he now is positioned trying to achieve expectations - maybe in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with neither fighter ready to be aggressive in a cagey initial rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who utilized a tight guard to barely take the better stanzas.
The spectators' acceptance diminished during frequent holding, with the challenger falling to the floor various instances during grappling.
Parker closed well, but many rounds were difficult to score. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just one round.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Hatton Memorial Inspires All-Manchester Battle
In the supporting bout, Lyndon Arthur beat Rea by divided decision in a outstanding local rivalry fight to capture the European light-heavyweight title.
The venue grew hushed for a extremely emotional tribute ahead of the contest as ten bells sounded in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the concluding sound faded, the quiet gave way to a chant of "there's just one Hatton".
The fighting inside the ropes matched the feeling. Arthur was knocked down by a significant blow squarely on the chin in the initial stage, rising shakily to his position on the referee's count.
But the red-colored attire of Arthur soon pressed ahead again. From the other corner, Rea - in competitive blue - was injured quickly, significant bruising forming under his face as the fighters exchanged punishing blows.
The challenger, 27, landed power punches but Arthur, thirty-four, matched the intensity with effective uppercuts as the intensity rarely dropped over twelve rounds.
The victor edged the result with judges scorecards of draw, 115-113 and clearer margin, but the two athletes were persistent and courageous, everything their inspiration Hatton stood for.
