British light heavyweight Joshua Buatsi secured a victory yet unimpressive debut to life under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a tight 10-round bout at the Manchester venue.
But Parker found success, delivering effective single shots in a contest where the techniques didn't complement each other, with constant grabbing spoiling the action.
The officials judged it 96-94 for to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest display but what defines champions? They win," Buatsi stated in the ring as he was faced negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an memorable fight with Callum Smith in last winter - to secure a 20th pro success.
Various analysts felt the challenger, 31, should have been awarded the win but the contender experienced the second defeat of his 28-fight professional journey.
The Champion Claims Victory in Uneventful Affair
The fighter's advancement has slowed in the past few years through promotional disputes and considerable time of lack of fights.
Previously predicted as the rising talent of UK boxing, he now stands trying to realize his potential - possibly in what seems like a ultimate opportunity - under fresh management.
He started carefully, with neither fighter ready to overcommit in a calculated opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, causing problems for the favorite, who worked behind a protective stance to edge the better stanzas.
The spectators' acceptance wore thin amid regular grabbing, with Parker going down multiple occasions during close exchanges.
The underdog closed well, but multiple periods were hard to judge. Although, former world champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the likes of heavy hitter David Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Inspires All-Manchester Fight
In the supporting bout, Lyndon Arthur overcame Rea by close verdict in a excellent local rivalry fight to win the continental belt.
The arena grew hushed for a profoundly moving homage prior to the bout as 10 bells sounded in memory of Manchester's own Ricky Hatton, who succumbed at age 46 in recently.
It was the first major televised match card in the city since the passing of Hatton. As the last bell ended, the quiet became a chant of "there's only one Hatton".
The action during the bout matched the feeling. Arthur was sent to the canvas by a powerful punch directly to the chin in the initial stage, getting up unsteadily to his feet on the referee's count.
But the red-colored equipment of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was injured early, noticeable damage appearing under his orbital area as the duo exchanged hard punches.
The challenger, 27, connected with strong blows but Arthur, thirty-four, responded in kind with powerful upward punches as the pace hardly diminished over twelve rounds.
The victor edged the verdict with scoring tallies of 114-114, 115-113 and wider gap, but the two athletes were persistent and full of heart, exactly what their hero the legend embodied.
