UK light-heavyweight Joshua Buatsi earned a win yet disappointing beginning to life under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a tight 10-round contest at the Manchester venue.
But Parker found success, delivering effective single shots in a fight where the techniques never quite clicked, with excessive holding disrupting the fight.
Two judges scored it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They prevail," the victor said in the ring as he was met by boos from the spectators.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to earn a 20th pro success.
Several boxing experts felt Parker, thirty-one, should have been awarded the victory but the Derbyshire fighter endured the second defeat of his 28-fight professional journey.
Buatsi Secures Win in Slow Match
His career development has stalled in the past few years through promotional disputes and extended periods of inactivity.
Once tipped as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a last chance - under fresh management.
He opened tentatively, with neither fighter ready to overcommit in a tentative opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after damaging his hand during the bout, was making just his second fight at the higher weight class.
By the middle rounds, the underdog had kept it close, making life awkward for Buatsi, who operated with a solid defense to edge the cleaner stanzas.
The crowd's patience diminished during regular grabbing, with the challenger going down various instances during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. However, previous titleholder the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just one round.
Buatsi advances, but with the presence of heavy hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Homage Motivates All-Manchester Fight
In the co-main event, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent local rivalry contest to win the European light heavyweight championship.
The stadium became quiet for a extremely emotional homage before the fight as a bell ceremony tolled in honor of Manchester's own Ricky Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the concluding sound disappeared, the quiet became a chant of "there's just one Ricky Hatton".
The competition inside the ropes equaled the sentiment. The eventual winner was floored by a left hook flush on the chin in the second round, standing uncertainly to his position on the count of eight.
But the Manchester United-red equipment of Arthur soon pressed ahead again. Across the ring, Rea - in opposing blue - was injured soon, noticeable damage developing under his eye as the duo traded powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the intensity seldom decreased over twelve rounds.
Arthur barely secured the verdict with scoring tallies of even score, 115-113 and 115-112, but each competitor were determined and courageous, everything their hero the legend stood for.
