UK light heavyweight Joshua Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a tight ten-round bout at the Manchester venue.
But Parker found success, delivering effective clean blows in a fight where the approaches never quite clicked, with frequent clinching spoiling the fight.
Two judges judged it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my best performance but how do champions respond? They succeed," the victor commented in the arena as he was met by disapproval from the audience.
The British fighter bounced back after his maiden career setback - an memorable fight with his previous opponent in February - to secure a 20th pro success.
Various analysts thought the challenger, 31, should have been awarded the victory but the Derbyshire fighter endured the second setback of his 28-match professional journey.
The Champion Claims Win in Slow Match
His career development has slowed in recent years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He opened tentatively, with both competitors prepared to take risks in a cagey early stages.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was making just his second appearance at light-heavyweight.
By the halfway stage, the underdog had made it competitive, causing problems for the favorite, who worked behind a protective stance to barely take the better rounds.
The crowd's patience decreased amid frequent holding, with Parker going down several times during clinches.
The underdog closed well, but many rounds were hard to judge. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for the challenger, awarding Buatsi just a single round.
Buatsi advances, but with the presence of heavy hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Homage Inspires All-Manchester Battle
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester fight to secure the European light-heavyweight championship.
The arena grew hushed for a deeply poignant homage prior to the bout as a bell ceremony tolled in honor of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised fight night in the location since Hatton's passing. As the concluding sound disappeared, the stillness gave way to a roar of "there's only one Ricky Hatton".
The fighting inside the ropes matched the feeling. Arthur was sent to the canvas by a left hook flush on the chin in the early round, rising shakily to his footing on the referee's count.
But the traditional red equipment of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was marked up quickly, significant bruising forming under his orbital area as the fighters traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the action rarely dropped over twelve rounds.
Arthur narrowly won the result with scoring tallies of 114-114, narrow lead and wider gap, but each competitor were persistent and courageous, everything their idol the legend represented.
