British light heavyweight Joshua Buatsi secured a victory yet unimpressive start to his career under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a split decision in a competitive 10-round bout at the Co-op Live Arena.
But the challenger found success, landing some telling clean blows in a contest where the approaches failed to mesh, with excessive holding spoiling the contest.
The scoring judges judged it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my best display but how do champions respond? They win," the victor commented in the arena as he was greeted with boos from the audience.
The British fighter got back to winning after his maiden career setback - an thrilling contest with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts believed the challenger, 31, deserved the victory but the contender suffered the second setback of his 28-bout professional journey.
Buatsi Claims Win in Slow Match
Buatsi's progress has stalled in recent times through management issues and long spells of lack of fights.
Once tipped as the rising talent of British boxing, he now stands trying to achieve expectations - maybe in what seems like a ultimate opportunity - under new promotional backing.
He opened tentatively, with neither fighter ready to overcommit in a cagey initial rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in 2022 after suffering a hand injury in the contest, was competing in only his second fight at the higher weight class.
By the halfway stage, Parker had made it competitive, causing problems for the favorite, who worked behind a solid defense to edge the more effective rounds.
The crowd's patience decreased during frequent holding, with the challenger going down several times during grappling.
The underdog closed well, but multiple periods were challenging to assess. Nevertheless, ex-champion Carl Frampton - working with the broadcast network - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the likes of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Hatton Memorial Fuels All-Manchester Fight
In the co-main event, Lyndon Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester fight to capture the European light-heavyweight championship.
The venue became quiet for a deeply poignant tribute ahead of the contest as ten bells tolled in memory of the city's native Ricky Hatton, who died at age 46 in last month.
It was the premier televised match card in the location since Hatton's death. As the last bell ended, the stillness became a chant of "there's just one Hatton".
The fighting during the bout matched the emotion. Arthur was sent to the canvas by a powerful punch squarely on the jaw in the early round, standing uncertainly to his footing on the count of eight.
But the red-colored shorts of Arthur soon pressed ahead again. Across the ring, the opponent - in opposing blue - was damaged soon, noticeable damage developing under his face as the fighters exchanged punishing blows.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with powerful upward punches as the pace seldom decreased over 12 rounds.
Arthur barely secured the decision with official scores of 114-114, 115-113 and clearer margin, but the two athletes were persistent and courageous, everything their idol the legend stood for.
