British light-heavyweight Joshua Buatsi secured a victory yet disappointing debut to his career under new promoters with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a competitive ten-round contest at the boxing arena.
But Parker had his moments, delivering effective individual punches in a fight where the approaches never quite clicked, with excessive holding spoiling the fight.
The scoring judges scored it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my best display but what defines champions? They succeed," Buatsi commented in the ringside as he was faced disapproval from the crowd.
The British fighter got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to claim a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, merited the win but the British boxer experienced the second loss of his 28-match professional journey.
The Champion Secures Win in Slow Match
His career development has slowed in the past few years through management issues and extended periods of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers ready to overcommit in a calculated initial rounds.
Parker, whose only previous defeat came at the lower weight class against his former opponent in 2022 after breaking his hand mid-fight, was competing in only his second appearance at the higher weight class.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who utilized a protective stance to narrowly win the better rounds.
The audience's tolerance diminished because of regular grabbing, with the challenger going down several times during clinches.
The underdog finished the stronger, but several stanzas were challenging to assess. However, ex-champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor progresses, but with the likes of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Motivates All-Manchester Contest
In the co-main event, Lyndon Arthur overcame Rea by divided decision in a terrific local rivalry battle to win the European light-heavyweight title.
The venue became quiet for a profoundly moving homage before the fight as a bell ceremony tolled in honor of local hero Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised match card in the urban center since Hatton's death. As the final chime ended, the quiet gave way to a chant of "only one Ricky Hatton".
The competition inside the ropes matched the emotion. The eventual winner was sent to the canvas by a significant blow directly to the chin in the initial stage, getting up unsteadily to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon came forward again. On the opposite side, the opponent - in rival City blue - was injured early, noticeable damage appearing under his eye as the pair traded powerful shots.
The challenger, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace hardly diminished over the full distance.
The victor barely secured the result with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were determined and full of heart, everything their idol the legend represented.
