UK light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a competitive ten-round bout at the boxing arena.
But the challenger had his moments, landing some telling individual punches in a match where the techniques failed to mesh, with constant grabbing spoiling the fight.
Two judges scored it 96-94 for to the winner, with the remaining official a even score.
"It wasn't my best display but what defines champions? They succeed," Buatsi stated in the ringside as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought the challenger, 31, merited the win but the Derbyshire fighter endured the second setback of his 28-match professional journey.
The Champion Secures Win in Dull Encounter
Buatsi's progress has plateaued in recent years through contract problems and long spells of inactivity.
Previously predicted as the future of UK boxing, he now finds himself trying to realize his potential - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter prepared to be aggressive in a tentative opening few rounds.
The challenger, whose single earlier setback 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, the underdog had stayed in contention, making life awkward for the favorite, who worked behind a protective stance to narrowly win the better periods.
The spectators' acceptance diminished during regular grabbing, with Parker falling to the floor various instances during clinches.
Parker ended stronger, but many rounds were hard to judge. Although, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Hatton Memorial Fuels All-Manchester Fight
In the secondary fight, Lyndon Arthur beat Rea by divided decision in a excellent all-Manchester contest to secure the continental title.
The stadium grew hushed for a deeply poignant homage before the fight as ten bells rang in honor of Manchester's own Ricky Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the concluding sound ended, the silence became a shout of "there's just one Ricky Hatton".
The fighting within the ring matched the feeling. Arthur was floored by a powerful punch squarely on the face in the early round, getting up unsteadily to his position on the referee's count.
But the traditional red shorts of the fighter soon advanced again. Across the ring, Rea - in competitive blue - was injured early, heavy swelling appearing under his eye as the duo exchanged hard punches.
Rea, 27, connected with strong blows but the champion, thirty-four, responded in kind with stinging uppercuts as the intensity hardly diminished over the full distance.
Arthur barely secured the verdict with official scores of 114-114, close margin and clearer margin, but the two athletes were persistent and full of heart, exactly what their inspiration Hatton embodied.
