UK light heavyweight Joshua Buatsi secured a victory yet disappointing debut to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a close ten-round bout at the Manchester venue.
But Parker found success, connecting with powerful clean blows in a match where the techniques never quite clicked, with frequent clinching disrupting the action.
The scoring judges judged it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest display but what defines champions? They prevail," Buatsi stated in the ringside as he was faced negative reactions from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Various analysts believed Parker, 31, merited the win but the British boxer endured the second setback of his 28-fight career.
Buatsi Earns Victory in Dull Affair
The fighter's advancement has slowed in the past few years through management issues and long spells of inactivity.
Previously predicted as the rising talent of British boxing, he now finds himself trying to realize his potential - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He began cautiously, with the two boxers prepared to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after breaking his hand during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for Buatsi, who worked behind a tight guard to edge the cleaner rounds.
The audience's tolerance decreased during constant clinching, with the challenger falling to the floor several times during close exchanges.
Parker finished the stronger, but many rounds were hard to judge. However, ex-champion the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - judging by this showing - still appears challenging.
Hatton Tribute Motivates All-Manchester Battle
In the secondary fight, Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester fight to capture the continental title.
The stadium fell silent for a deeply poignant homage prior to the bout as ten bells sounded in remembrance of local hero Hatton, who passed away at age 46 in recently.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the concluding sound disappeared, the stillness transitioned to a chant of "only one Hatton".
The fighting within the ring reflected the emotion. The eventual winner was floored by a powerful punch directly to the face in the initial stage, getting up unsteadily to his footing on the eight count.
But the red-colored attire of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was injured quickly, noticeable damage appearing under his eye as the fighters traded hard punches.
Rea, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with effective uppercuts as the pace rarely dropped over the full distance.
The victor barely secured the verdict with official scores of draw, close margin and wider gap, but both fighters were persistent and courageous, exactly what their hero Hatton stood for.
