British light heavyweight Joshua Buatsi earned a win yet unimpressive beginning to life under new promoters with a decision win over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a split decision in a tight ten-round contest at the boxing arena.
But Parker found success, connecting with powerful clean blows in a match where the techniques never quite clicked, with constant grabbing spoiling the fight.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest display but what defines champions? They succeed," the victor stated in the ringside as he was faced negative reactions from the audience.
The Londoner returned to winning ways after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a 20th pro success.
Some ringside observers believed the challenger, thirty-one, should have been awarded the victory but the British boxer experienced the second setback of his 28-bout professional journey.
Buatsi Earns Win in Uneventful Affair
His career development has plateaued in the past few years through management issues and extended periods of lack of fights.
Once tipped as the next star of the British fight scene, he now finds himself trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter ready to overcommit in a tentative opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second bout at light heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who utilized a solid defense to barely take the better stanzas.
The crowd's patience wore thin amid frequent holding, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog finished the stronger, but many rounds were challenging to assess. However, former world champion the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor moves on, but with the presence of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - on this evidence - still looks steep.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the supporting bout, Lyndon Arthur overcame Bradley Rea by divided decision in a excellent Manchester vs Manchester battle to capture the continental championship.
The venue became quiet for a deeply poignant memorial ahead of the contest as 10 bells rang in honor of local hero Hatton, who passed away aged 46 in last month.
It was the first major televised match card in the location since the passing of Hatton. As the concluding sound ended, the quiet became a roar of "only one Ricky Hatton".
The action within the ring reflected the sentiment. The eventual winner was sent to the canvas by a left hook squarely on the jaw in the early round, getting up unsteadily to his feet on the eight count.
But the traditional red equipment of Arthur soon came forward again. From the other corner, Rea - in rival City blue - was injured early, significant bruising appearing under his eye as the pair exchanged powerful shots.
The challenger, 27, landed power punches but the champion, 34, responded in kind with stinging uppercuts as the pace hardly diminished over twelve rounds.
The victor edged the decision with scoring tallies of 114-114, 115-113 and clearer margin, but each competitor were determined and courageous, exactly what their idol the legend stood for.
