UK light-heavyweight Joshua Buatsi made a winning yet disappointing beginning to life 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 bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful single shots in a match where the techniques failed to mesh, with excessive holding spoiling the contest.
The scoring judges judged it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my best showing but how do champions respond? They prevail," Buatsi stated in the ring as he was faced boos from the crowd.
The Londoner got back to winning after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Some ringside observers thought the challenger, thirty-one, merited the win but the contender experienced the second loss of his 28-bout professional journey.
Buatsi Earns Win in Dull Affair
The fighter's advancement has stalled in the past few years through management issues and extended periods of inactivity.
Previously predicted as the next star of UK boxing, he now finds himself trying to fulfil that early promise - maybe in what seems like a last chance - under fresh management.
He started carefully, with neither fighter ready to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had made it competitive, making life awkward for the favorite, who utilized a tight guard to narrowly win the cleaner rounds.
The audience's tolerance wore thin because of frequent holding, with Parker falling to the floor multiple occasions during grappling.
The underdog finished the stronger, but multiple periods were challenging to assess. Although, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the journey to titles - on this evidence - still looks steep.
Hatton Homage Fuels Manchester Derby Fight
In the secondary fight, Arthur defeated Bradley Rea by close verdict in a terrific all-Manchester fight to capture the continental title.
The venue fell silent for a extremely emotional tribute ahead of the contest as a bell ceremony tolled in remembrance of the city's native Hatton, who passed away aged 46 in September.
It was the premier televised boxing event in the city since the passing of Hatton. As the final chime faded, the silence became a roar of "there's just one Hatton".
The fighting during the bout reflected the feeling. Arthur was floored by a significant blow flush on the face in the second round, standing uncertainly to his feet on the eight count.
But the traditional red attire of the fighter soon advanced again. Across the ring, Rea - in competitive blue - was injured soon, heavy swelling forming under his eye as the fighters exchanged hard punches.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the action rarely dropped over twelve rounds.
Arthur narrowly won the verdict with judges scorecards of 114-114, narrow lead and clearer margin, but each competitor were relentless and courageous, everything their idol Hatton represented.
