British light-heavyweight Joshua Buatsi made a winning yet unimpressive start to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a close ten-round contest at the Co-op Live Arena.
But Parker found success, delivering effective single shots in a contest where the approaches never quite clicked, with constant grabbing spoiling the fight.
The scoring judges judged it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They prevail," the victor said in the ringside as he was faced negative reactions from the audience.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a 20th pro success.
Various analysts felt the challenger, thirty-one, should have been awarded the victory but the contender experienced the second setback of his 28-match career.
The Champion Earns Win in Dull Match
His career development has stalled in recent times through promotional disputes and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to achieve expectations - possibly in what seems like a last chance - under recent support.
He opened tentatively, with neither fighter willing to overcommit in a tentative early stages.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in 2022 after damaging his hand during the bout, was competing in only his second fight at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who operated with a solid defense to narrowly win the better periods.
The crowd's patience decreased amid frequent holding, with the challenger falling to the floor multiple occasions during clinches.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion Carl Frampton - providing analysis for Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Tribute Inspires All-Manchester Contest
In the supporting bout, Lyndon Arthur defeated Rea by split-decision in a outstanding Manchester vs Manchester battle to capture the continental title.
The stadium fell silent for a profoundly moving memorial before the fight as a bell ceremony sounded in remembrance of the city's native Hatton, who died 46 years old in last month.
It was the premier televised boxing event in the city since Hatton's passing. As the final chime faded, the quiet gave way to a chant of "only one Ricky Hatton".
The action inside the ropes reflected the sentiment. Arthur was floored by a significant blow squarely on the jaw in the second round, standing uncertainly to his position on the eight count.
But the traditional red shorts of Arthur soon pressed ahead again. Across the ring, Rea - in opposing blue - was injured quickly, heavy swelling appearing under his orbital area as the fighters traded powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace rarely dropped over twelve rounds.
Arthur narrowly won the verdict with official scores of draw, narrow lead and clearer margin, but both fighters were relentless and brave, everything their idol the legend represented.
