British light-heavyweight Joshua Buatsi made a winning yet underwhelming debut to life under fresh promotional backing 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 tight 10-round fight at the boxing arena.
But the challenger found success, connecting with powerful clean blows in a match where the techniques never quite clicked, with frequent clinching disrupting the contest.
The scoring judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my finest showing but what do champions do? They succeed," the victor stated in the ringside as he was faced negative reactions from the spectators.
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 career victory.
Some ringside observers thought Parker, thirty-one, deserved the decision but the British boxer suffered the second defeat of his 28-match professional journey.
Buatsi Secures Win in Slow Encounter
His career development has stalled in recent years through contract problems and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to achieve expectations - 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 cagey early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for the favorite, who utilized a solid defense to edge the more effective rounds.
The audience's tolerance wore thin amid frequent holding, with the challenger falling to the floor various instances during close exchanges.
The underdog ended stronger, but many rounds were hard to judge. However, ex-champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi advances, but with the likes of hard hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Hatton Homage Fuels All-Manchester Battle
In the secondary fight, Arthur overcame Rea by close verdict in a terrific local rivalry battle to capture the continental championship.
The venue became quiet for a profoundly moving tribute prior to the bout as 10 bells sounded in memory of the city's native Hatton, who passed away at age 46 in recently.
It was the first major televised fight night in the location since the passing of Hatton. As the last bell ended, the silence gave way to a chant of "there's just one Ricky Hatton".
The competition during the bout equaled the feeling. The eventual winner was floored by a significant blow squarely on the jaw in the early round, standing uncertainly to his position on the count of eight.
But the traditional red equipment of Arthur soon came forward again. Across the ring, the opponent - in rival City blue - was injured early, noticeable damage forming under his eye as the duo landed punishing blows.
The challenger, 27, landed power punches but the champion, thirty-four, fought fire with fire with effective uppercuts as the action seldom decreased over the full distance.
The victor edged the decision with official scores of 114-114, 115-113 and wider gap, but the two athletes were relentless and courageous, all the qualities their inspiration the legend represented.
