UK light-heavyweight Joshua Buatsi earned a win yet underwhelming beginning to his career under new promoters with a decision win over Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a competitive ten-round contest at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful clean blows in a contest where the techniques didn't complement each other, with frequent clinching disrupting the contest.
The officials judged it 96-94 to the winner, with the third a 95-95.
"It wasn't my finest performance but what defines champions? They win," Buatsi stated in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a 20th career victory.
Various analysts felt the challenger, 31, deserved the victory but the contender experienced the second setback of his 28-fight career.
Buatsi Secures Win in Slow Affair
Buatsi's progress has plateaued in the past few years through promotional disputes and long spells of lack of fights.
Previously predicted as the future of the British fight scene, he now finds himself trying to achieve expectations - possibly in what appears to be a final roll of the dice - under fresh management.
He opened tentatively, with neither fighter prepared to overcommit in a calculated initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was making just his second fight at the higher weight class.
By the middle rounds, the underdog had kept it close, making life awkward for Buatsi, who worked behind a protective stance to narrowly win the more effective rounds.
The spectators' acceptance wore thin amid frequent holding, with the challenger going down various instances during close exchanges.
The underdog ended stronger, but several stanzas were difficult to score. However, former world champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - judging by this showing - still seems difficult.
Hatton Homage Inspires Local Rivalry Fight
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a terrific Manchester vs Manchester contest to capture the European light-heavyweight belt.
The venue became quiet for a extremely emotional tribute ahead of the contest as 10 bells rang in memory of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the final chime ended, the silence transitioned to a chant of "only one Hatton".
The action inside the ropes equaled the feeling. Arthur was knocked down by a powerful punch squarely on the face in the second round, getting up unsteadily to his position on the eight count.
But the Manchester United-red attire of Arthur soon advanced again. Across the ring, Rea - in rival City blue - was marked up quickly, noticeable damage forming under his face as the duo landed punishing blows.
The challenger, 27, delivered effective strikes but the champion, thirty-four, responded in kind with effective uppercuts as the action hardly diminished over 12 rounds.
The victor edged the verdict with judges scorecards of 114-114, close margin and 115-112, but each competitor were determined and courageous, all the qualities their inspiration Hatton embodied.
