British light-heavyweight Joshua Buatsi made a winning yet unimpressive start to life under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a close 10-round bout at the boxing arena.
But the challenger found success, connecting with powerful clean blows in a contest where the approaches failed to mesh, with excessive holding spoiling the action.
Two judges had it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best performance but what do champions do? They succeed," the victor stated in the ring as he was met by negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Various analysts thought the challenger, 31, should have been awarded the victory but the British boxer endured the second defeat of his 28-match professional journey.
Buatsi Earns Win in Uneventful Encounter
The fighter's advancement has plateaued in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the future of UK boxing, he now is positioned trying to realize his potential - perhaps in what seems like a last chance - under fresh management.
He began cautiously, with the two boxers ready to overcommit in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second fight at light-heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for the favorite, who worked behind a solid defense to narrowly win the cleaner rounds.
The spectators' acceptance decreased during frequent holding, with Parker going down multiple occasions during clinches.
Parker ended stronger, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, giving Buatsi just only one stanza.
The victor moves on, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a terrific local rivalry battle to secure the continental belt.
The stadium became quiet for a profoundly moving memorial ahead of the contest as 10 bells tolled in honor of Manchester's own Hatton, who passed away at age 46 in September.
It was the first major televised match card in the location since the passing of Hatton. As the concluding sound ended, the silence gave way to a shout of "there's only one Hatton".
The fighting within the ring equaled the emotion. The eventual winner was floored by a left hook squarely on the jaw in the early round, standing uncertainly to his footing on the referee's count.
But the traditional red equipment of the fighter soon advanced again. Across the ring, the opponent - in competitive blue - was marked up early, significant bruising appearing under his face as the fighters landed powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, 34, matched the intensity with stinging uppercuts as the action rarely dropped over 12 rounds.
The victor barely secured the result with judges scorecards of even score, close margin and clearer margin, but both fighters were persistent and brave, exactly what their idol Hatton stood for.
