British light heavyweight Joshua Buatsi secured a victory yet underwhelming debut to his career under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a close 10-round bout at the boxing arena.
But Parker had his moments, connecting with powerful clean blows in a contest where the techniques never quite clicked, with constant grabbing marring the fight.
The officials scored it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my best performance but what do champions do? They succeed," Buatsi commented in the ringside as he was faced boos from the crowd.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Various analysts felt the challenger, 31, deserved the win but the contender experienced the second loss of his 28-fight career.
Buatsi Earns Win in Uneventful Match
Buatsi's progress has plateaued in recent years through contract problems and extended periods of lack of fights.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to realize his potential - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with the two boxers willing to take risks in a tentative initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second appearance at light heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who utilized a tight guard to barely take the cleaner stanzas.
The audience's tolerance diminished because of frequent holding, with Parker going down various instances during clinches.
The underdog closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
The victor progresses, but with the presence of hard hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the co-main event, Arthur overcame Bradley Rea by divided decision in a outstanding Manchester vs Manchester contest to capture the European light-heavyweight belt.
The arena became quiet for a extremely emotional memorial before the fight as a bell ceremony tolled in honor of Manchester's own Hatton, who succumbed at age 46 in last month.
It was the first major televised boxing event in the urban center since Hatton's death. As the last bell ended, the stillness gave way to a shout of "there's just one Ricky Hatton".
The competition inside the ropes equaled the emotion. Arthur was floored by a left hook directly to the face in the early round, rising shakily to his position on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was damaged soon, significant bruising developing under his eye as the duo traded hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the intensity rarely dropped over twelve rounds.
Arthur barely secured the decision with scoring tallies of 114-114, 115-113 and 115-112, but each competitor were determined and full of heart, all the qualities their idol the legend represented.
