British light heavyweight Buatsi made a winning yet disappointing debut to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a close ten-round bout at the boxing arena.
But Parker found success, delivering effective individual punches in a contest where the styles never quite clicked, with constant grabbing spoiling the action.
Two judges had it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my best performance but how do champions respond? They succeed," Buatsi stated in the ringside as he was met by disapproval from the crowd.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to earn a 20th pro success.
Some ringside observers thought Parker, 31, should have been awarded the decision but the Derbyshire fighter suffered the second defeat of his 28-fight career.
The Champion Claims Victory in Uneventful Encounter
His career development has slowed in recent times through promotional disputes and considerable time of lack of fights.
Once tipped as the rising talent of UK boxing, he now is positioned trying to realize his potential - perhaps in what appears to be a final roll of the dice - under fresh management.
He started carefully, with the two boxers prepared to overcommit in a cagey early stages.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second fight at the higher weight class.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who operated with a solid defense to barely take the cleaner stanzas.
The crowd's patience decreased during constant clinching, with the challenger going down various instances during grappling.
Parker closed well, but several stanzas were difficult to score. Nevertheless, former world champion the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the likes of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Fuels Local Rivalry Battle
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a outstanding all-Manchester contest to win the European light heavyweight belt.
The arena became quiet for a profoundly moving homage prior to the bout as a bell ceremony sounded in remembrance of the city's native Ricky Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the last bell ended, the quiet transitioned to a chant of "there's just one Hatton".
The fighting within the ring equaled the sentiment. The eventual winner was knocked down by a significant blow directly to the jaw in the second round, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red attire of Arthur soon pressed ahead again. From the other corner, the opponent - in competitive blue - was damaged quickly, noticeable damage appearing under his orbital area as the duo landed hard punches.
The challenger, 27, connected with strong blows but Arthur, 34, matched the intensity with stinging uppercuts as the pace hardly diminished over the full distance.
Arthur barely secured the decision with scoring tallies of 114-114, narrow lead and wider gap, but the two athletes were determined and courageous, exactly what their hero the legend stood for.
