British light-heavyweight Joshua Buatsi made a winning yet disappointing debut to life under new promoters with a points victory over Parker in Manchester.
The Olympic medal winner's punch output likely gained him a majority decision in a tight 10-round bout at the boxing arena.
But the challenger had his moments, landing some telling individual punches in a match where the approaches failed to mesh, with constant grabbing marring the action.
The scoring judges judged it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my greatest performance but what defines champions? They win," the victor said in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with his previous opponent in February - to secure a 20th career victory.
Some ringside observers believed the challenger, thirty-one, merited the win but the British boxer suffered the second setback of his 28-match career.
The Champion Earns Triumph in Uneventful Affair
Buatsi's progress has slowed in the past few years through management issues and long spells of inactivity.
Previously predicted as the rising talent of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers ready to take risks in a calculated early stages.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second bout at light-heavyweight.
By the middle rounds, the underdog had kept it close, making life awkward for the favorite, who operated with a solid defense to edge the cleaner stanzas.
The crowd's patience decreased because of constant clinching, with the challenger falling to the floor various instances during clinches.
The underdog closed well, but several stanzas were challenging to assess. Although, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to capture the European light-heavyweight title.
The arena grew hushed for a profoundly moving memorial ahead of the contest as 10 bells tolled in remembrance of Manchester's own Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the city since Hatton's passing. As the concluding sound ended, the silence became a shout of "there's just one Ricky Hatton".
The competition inside the ropes matched the feeling. The eventual winner was sent to the canvas by a significant blow squarely on the jaw in the initial stage, rising shakily to his position on the count of eight.
But the traditional red equipment of Arthur soon came forward again. Across the ring, the opponent - in competitive blue - was marked up early, significant bruising appearing under his orbital area as the pair traded punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the intensity rarely dropped over the full distance.
Arthur edged the result with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were relentless and courageous, all the qualities their hero the legend embodied.
