British light-heavyweight Joshua Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a tight 10-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful single shots in a fight where the techniques never quite clicked, with frequent clinching disrupting the contest.
Two judges judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my finest performance but what do champions do? They win," Buatsi said in the ring as he was faced negative reactions from the crowd.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to claim a 20th career victory.
Some ringside observers felt Parker, 31, merited the victory but the contender endured the second setback of his 28-match professional journey.
The Champion Secures Triumph in Uneventful Match
Buatsi's progress has stalled in recent times through management issues and extended periods of lack of fights.
Previously predicted as the future of British boxing, he now is positioned trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He opened tentatively, with both competitors prepared to be aggressive in a cagey opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was competing in only his second appearance at light-heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who worked behind a tight guard to barely take the better periods.
The audience's tolerance decreased amid frequent holding, with the challenger falling to the floor several times during close exchanges.
Parker ended stronger, but multiple periods were difficult to score. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just a single round.
The victor advances, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Hatton Tribute Motivates All-Manchester Contest
In the co-main event, Arthur defeated Bradley Rea by close verdict in a terrific Manchester vs Manchester contest to capture the European light-heavyweight title.
The arena became quiet for a profoundly moving homage ahead of the contest as ten bells sounded in remembrance of the city's native Hatton, who passed away at age 46 in last month.
It was the premier televised fight night in the city since the passing of Hatton. As the last bell faded, the quiet gave way to a roar of "there's only one Ricky Hatton".
The fighting inside the ropes equaled the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the early round, rising shakily to his feet on the count of eight.
But the traditional red equipment of the fighter soon came forward again. From the other corner, Rea - in opposing blue - was injured quickly, heavy swelling developing under his eye as the duo landed punishing blows.
The challenger, 27, connected with strong blows but the champion, thirty-four, responded in kind with stinging uppercuts as the intensity seldom decreased over twelve rounds.
The victor barely secured the result with judges scorecards of draw, narrow lead and wider gap, but both fighters were persistent and brave, everything their idol Hatton stood for.
