UK light heavyweight Joshua Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a competitive ten-round fight at the boxing arena.
But the challenger found success, connecting with powerful single shots in a contest where the approaches failed to mesh, with excessive holding spoiling the contest.
The officials scored it 96-94 for to the winner, with the third a even score.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi commented in the arena as he was met by boos from the spectators.
The Londoner got back to winning after his first professional defeat - an memorable fight with his previous opponent in February - to secure a twentieth professional win.
Some ringside observers believed Parker, 31, merited the victory but the Derbyshire fighter suffered the second defeat of his 28-bout career.
Buatsi Secures Victory in Uneventful Affair
Buatsi's progress has stalled in recent years through promotional disputes and considerable time of lack of fights.
Previously predicted as the future of the British fight scene, he now is positioned trying to realize his potential - perhaps in what feels like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors ready to overcommit in a cagey early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand in the contest, was making just his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to barely take the better rounds.
The crowd's patience wore thin amid constant clinching, with the challenger slipping to the canvas multiple occasions during grappling.
The underdog finished the stronger, but multiple periods were hard to judge. However, ex-champion the boxing analyst - working with 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 Benavidez, and Russian champion Bivol leading the category, the road to world glory - judging by this showing - still appears challenging.
Hatton Tribute Motivates All-Manchester Battle
In the supporting bout, Arthur beat Rea by split-decision in a outstanding Manchester vs Manchester battle to secure the European light-heavyweight title.
The stadium grew hushed for a extremely emotional homage before the fight as a bell ceremony rang in remembrance of the city's native Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the urban center since Hatton's passing. As the concluding sound ended, the silence became a chant of "there's just one Hatton".
The fighting during the bout equaled the feeling. Arthur was knocked down by a significant blow squarely on the jaw in the initial stage, standing uncertainly to his position on the eight count.
But the Manchester United-red attire of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was damaged quickly, noticeable damage forming under his face as the fighters landed punishing blows.
The challenger, 27, connected with strong blows but Arthur, 34, responded in kind with powerful upward punches as the pace hardly diminished over twelve rounds.
The victor edged the verdict with judges scorecards of 114-114, close margin and wider gap, but the two athletes were determined and full of heart, all the qualities their inspiration Hatton stood for.
