British light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under new promoters with a unanimous decision over Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a tight ten-round contest at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful single shots in a contest where the styles failed to mesh, with constant grabbing disrupting the fight.
The officials had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They succeed," the victor stated in the ringside as he was faced negative reactions from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to earn a 20th pro success.
Various analysts thought the challenger, 31, merited the decision but the Derbyshire fighter experienced the second setback of his 28-match career.
The Champion Secures Win in Uneventful Affair
Buatsi's progress has plateaued in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the future of UK boxing, he now finds himself trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with neither fighter ready to overcommit in a cagey opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to barely take the more effective periods.
The spectators' acceptance decreased because of frequent holding, with the challenger slipping to the canvas various instances during grappling.
The underdog finished the stronger, but several stanzas were challenging to assess. Although, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the presence of power puncher David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Homage Inspires All-Manchester Contest
In the co-main event, Arthur overcame Bradley Rea by close verdict in a outstanding local rivalry fight to secure the European light-heavyweight title.
The arena grew hushed for a extremely emotional tribute ahead of the contest as a bell ceremony sounded in memory of local hero Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast boxing event in the city since Hatton's passing. As the final chime disappeared, the quiet became a roar of "there's only one Hatton".
The fighting inside the ropes equaled the sentiment. The eventual winner was knocked down by a left hook squarely on the jaw in the initial stage, getting up unsteadily to his feet on the eight count.
But the Manchester United-red attire of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was marked up early, heavy swelling forming under his eye as the pair traded powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, responded in kind with effective uppercuts as the intensity rarely dropped over the full distance.
The victor narrowly won the verdict with scoring tallies of 114-114, narrow lead and 115-112, but each competitor were persistent and full of heart, all the qualities their inspiration the legend embodied.
