UK light heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under fresh promotional backing with a points victory over Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a judges' verdict in a tight ten-round fight at the boxing arena.
But Parker landed significant shots, delivering effective clean blows in a fight where the styles failed to mesh, with excessive holding disrupting the contest.
Two judges scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my greatest performance but what do champions do? They succeed," Buatsi said in the ringside as he was greeted with negative reactions from the audience.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in last winter - to claim a 20th pro success.
Some ringside observers thought Parker, 31, deserved the win but the Derbyshire fighter experienced the second loss of his 28-bout professional journey.
Buatsi Claims Victory in Uneventful Encounter
His career development has stalled in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now is positioned trying to realize his potential - maybe in what feels like a last chance - under new promotional backing.
He opened tentatively, with both competitors willing to take risks in a tentative opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was making just his second bout at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who utilized a solid defense to edge the cleaner rounds.
The crowd's patience diminished during regular grabbing, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog closed well, but multiple periods were difficult to score. Although, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - judging by this showing - still appears challenging.
Ricky Hatton Memorial Inspires Local Rivalry Battle
In the co-main event, Arthur overcame Rea by split-decision in a excellent all-Manchester fight to secure the European light heavyweight belt.
The arena fell silent for a deeply poignant tribute before the fight as ten bells sounded in memory of Manchester's own Hatton, who succumbed 46 years old in recently.
It was the premier televised match card in the city since the passing of Hatton. As the final chime faded, the stillness gave way to a chant of "there's just one Hatton".
The action within the ring reflected the feeling. Arthur was sent to the canvas by a significant blow flush on the jaw in the early round, getting up unsteadily to his footing on the count of eight.
But the traditional red equipment of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was injured quickly, heavy swelling appearing under his face as the duo traded hard punches.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
Arthur narrowly won the result with scoring tallies of 114-114, narrow lead and wider gap, but the two athletes were relentless and courageous, exactly what their hero the legend embodied.
