British light heavyweight Buatsi made a winning yet disappointing start to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a competitive 10-round bout at the Manchester venue.
But the challenger found success, landing some telling single shots in a match where the approaches failed to mesh, with constant grabbing disrupting the fight.
The officials had it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest display but what defines champions? They win," the victor said in the ringside as he was greeted with boos from the spectators.
The Londoner got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a 20th pro success.
Some ringside observers believed the challenger, thirty-one, merited the decision but the Derbyshire fighter suffered the second loss of his 28-fight professional journey.
The Champion Claims Triumph in Uneventful Affair
The fighter's advancement has plateaued in the past few years through contract problems and long spells of inactivity.
Earlier forecast as the future of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what feels like a final roll of the dice - under fresh management.
He started carefully, with neither fighter ready to take risks in a cagey opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after breaking his hand in the contest, was making just his second fight at light heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who operated with a protective stance to edge the cleaner rounds.
The crowd's patience decreased amid frequent holding, with the challenger going down several times during close exchanges.
The underdog closed well, but several stanzas were hard to judge. Nevertheless, previous titleholder the boxing analyst - commentating on Dazn - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of power puncher David Benavidez, and Russian star Bivol leading the category, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Tribute Fuels Manchester Derby Fight
In the secondary fight, Arthur overcame Rea by close verdict in a terrific local rivalry contest to win the European light heavyweight championship.
The arena fell silent for a deeply poignant homage ahead of the contest as ten bells rang in memory of the city's native Hatton, who died aged 46 in September.
It was the premier televised boxing event in the city since Hatton's death. As the concluding sound disappeared, the quiet became a roar of "there's just one Ricky Hatton".
The action within the ring matched the sentiment. The eventual winner was knocked down by a left hook flush on the jaw in the initial stage, getting up unsteadily to his feet on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was marked up early, noticeable damage forming under his eye as the fighters exchanged powerful shots.
The challenger, 27, landed power punches but Arthur, 34, responded in kind with stinging uppercuts as the action rarely dropped over twelve rounds.
Arthur edged the result with official scores of 114-114, 115-113 and wider gap, but both fighters were relentless and full of heart, everything their inspiration Hatton embodied.
