UK light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a majority decision in a close 10-round contest at the Co-op Live Arena.
But Parker landed significant shots, landing some telling individual punches in a match where the styles never quite clicked, with excessive holding spoiling the fight.
Two judges had it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They win," Buatsi stated in the ring as he was met by disapproval from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers felt the challenger, thirty-one, merited the win but the contender suffered the second setback of his 28-match professional journey.
Buatsi Earns Triumph in Uneventful Affair
His career development has stalled in recent years through contract problems and considerable time of inactivity.
Once tipped as the future of British boxing, he now is positioned trying to achieve expectations - possibly in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors prepared to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was participating in his second fight at light-heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who utilized a solid defense to edge the cleaner rounds.
The spectators' acceptance wore thin amid frequent holding, with the challenger falling to the floor several times during clinches.
Parker closed well, but many rounds were difficult to score. Nevertheless, ex-champion Carl Frampton - commentating on the broadcast network - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Motivates Manchester Derby Fight
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a excellent Manchester vs Manchester battle to capture the continental championship.
The arena became quiet for a profoundly moving homage before the fight as ten bells rang in memory of the city's native Ricky Hatton, who succumbed at age 46 in recently.
It was the first major televised fight night in the location since Hatton's passing. As the last bell faded, the stillness gave way to a shout of "there's just one Hatton".
The fighting inside the ropes equaled the sentiment. The eventual winner was floored by a powerful punch flush on the jaw in the second round, rising shakily to his position on the eight count.
But the traditional red attire of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up quickly, noticeable damage developing under his face as the duo exchanged hard punches.
The challenger, 27, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
The victor edged the verdict with official scores of 114-114, narrow lead and wider gap, but the two athletes were persistent and full of heart, exactly what their hero Hatton embodied.
