British light heavyweight Joshua Buatsi earned a win yet underwhelming beginning to life under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight 10-round fight at the boxing arena.
But Parker had his moments, connecting with powerful single shots in a fight where the techniques didn't complement each other, with frequent clinching marring the action.
The scoring judges judged it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They prevail," Buatsi commented in the arena as he was faced boos from the audience.
The British fighter got back to winning after his initial pro loss - an memorable fight with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts believed Parker, 31, merited the win but the British boxer suffered the second loss of his 28-bout career.
Buatsi Earns Triumph in Dull Match
The fighter's advancement has stalled in the past few years through promotional disputes and considerable time of lack of fights.
Previously predicted as the rising talent of British boxing, he now stands trying to achieve expectations - perhaps in what appears to be a ultimate opportunity - under recent support.
He started carefully, with the two boxers willing to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who operated with a protective stance to narrowly win the cleaner periods.
The spectators' acceptance diminished during constant clinching, with Parker slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. Although, former world champion Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the presence of power puncher Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - on this evidence - still appears challenging.
Hatton Tribute Fuels Local Rivalry Contest
In the secondary fight, Arthur overcame Rea by split-decision in a excellent all-Manchester battle to win the European light-heavyweight belt.
The stadium grew hushed for a deeply poignant homage prior to the bout as ten bells rang in memory of Manchester's own Ricky Hatton, who died 46 years old in last month.
It was the first major televised match card in the city since the passing of Hatton. As the final chime ended, the quiet gave way to a chant of "there's just one Hatton".
The fighting during the bout reflected the feeling. The eventual winner was knocked down by a significant blow flush on the jaw in the early round, getting up unsteadily to his position on the eight count.
But the red-colored attire of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was injured early, heavy swelling appearing under his eye as the pair traded punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, responded in kind with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the verdict with scoring tallies of even score, close margin and 115-112, but the two athletes were determined and full of heart, exactly what their inspiration Hatton represented.
