British light-heavyweight Joshua Buatsi secured a victory yet unimpressive debut to his career under new promoters with a decision win over Parker in Manchester.
The Olympic medal winner's work rate likely gained him a split decision in a competitive ten-round fight at the Manchester venue.
But Parker found success, landing some telling single shots in a contest where the techniques failed to mesh, with constant grabbing marring the action.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest performance but how do champions respond? They prevail," the victor commented in the ringside as he was met by disapproval from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Several boxing experts thought the challenger, thirty-one, should have been awarded the decision but the Derbyshire fighter experienced the second loss of his 28-match career.
Buatsi Secures Win in Dull Match
The fighter's advancement has plateaued in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to achieve expectations - possibly in what feels like a last chance - under new promotional backing.
He began cautiously, with both competitors prepared to take risks in a tentative early stages.
Parker, whose sole prior loss came at super-middleweight against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who operated with a solid defense to edge the cleaner periods.
The audience's tolerance wore thin during frequent holding, with Parker slipping to the canvas multiple occasions during close exchanges.
Parker finished the stronger, but multiple periods were challenging to assess. However, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Russian champion Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Hatton Memorial Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur defeated Rea by divided decision in a terrific all-Manchester contest to capture the European light heavyweight title.
The arena grew hushed for a extremely emotional homage before the fight as a bell ceremony rang in honor of local hero Ricky Hatton, who succumbed 46 years old in recently.
It was the first major televised match card in the urban center since Hatton's death. As the final chime faded, the silence became a chant of "there's just one Hatton".
The action inside the ropes reflected the feeling. Arthur was knocked down by a significant blow squarely on the face in the early round, standing uncertainly to his footing on the eight count.
But the red-colored shorts of Arthur soon advanced again. From the other corner, Rea - in competitive blue - was injured quickly, noticeable damage developing under his orbital area as the fighters landed hard punches.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with stinging uppercuts as the intensity rarely dropped over the full distance.
Arthur edged the result with judges scorecards of draw, close margin and clearer margin, but each competitor were relentless and brave, everything their hero Hatton stood for.
