British light-heavyweight Joshua Buatsi earned a win yet unimpressive start to life under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a close ten-round contest at the Manchester venue.
But Parker had his moments, landing some telling single shots in a match where the techniques didn't complement each other, with constant grabbing marring the fight.
The officials scored it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my finest display but what do champions do? They win," the victor commented in the arena as he was faced negative reactions from the spectators.
The British fighter bounced back after his initial pro loss - an memorable fight with Callum Smith in last winter - to earn a 20th career victory.
Some ringside observers thought the challenger, thirty-one, deserved the decision but the contender suffered the second loss of his 28-match professional journey.
The Champion Claims Triumph in Slow Match
His career development has slowed in the past few years through contract problems and long spells of inactivity.
Previously predicted as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - maybe in what appears to be a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers willing to be aggressive in a tentative initial rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second appearance at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for Buatsi, who worked behind a tight guard to barely take the cleaner periods.
The crowd's patience wore thin amid regular grabbing, with the challenger falling to the floor various instances during clinches.
The underdog closed well, but multiple periods were difficult to score. Although, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for Parker, giving Buatsi just one round.
The victor moves on, but with the caliber of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Homage Motivates Manchester Derby Fight
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding local rivalry fight to capture the European light-heavyweight title.
The arena grew hushed for a deeply poignant tribute before the fight as ten bells sounded in memory of local hero Hatton, who passed away at age 46 in recently.
It was the initial significant broadcast match card in the location since Hatton's passing. As the final chime disappeared, the stillness became a shout of "only one Ricky Hatton".
The fighting during the bout matched the emotion. Arthur was floored by a powerful punch directly to the chin in the early round, standing uncertainly to his footing on the eight count.
But the red-colored attire of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was damaged early, noticeable damage appearing under his eye as the duo landed punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with powerful upward punches as the intensity rarely dropped over 12 rounds.
Arthur edged the verdict with judges scorecards of even score, narrow lead and clearer margin, but each competitor were relentless and courageous, everything their idol Hatton embodied.
