British light heavyweight Buatsi secured a victory yet underwhelming start to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a close 10-round bout at the boxing arena.
But Parker landed significant shots, delivering effective clean blows in a contest where the techniques didn't complement each other, with excessive holding disrupting the contest.
Two judges scored it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to secure a 20th career victory.
Several boxing experts believed the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second setback of his 28-bout career.
Buatsi Earns Triumph in Slow Encounter
Buatsi's progress has plateaued in the past few years through management issues and long spells of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to achieve expectations - maybe in what feels like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter prepared to overcommit in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after damaging his hand in the contest, was competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had made it competitive, creating difficulties for Buatsi, who operated with a protective stance to barely take the more effective stanzas.
The spectators' acceptance decreased during frequent holding, with the challenger falling to the floor several times during close exchanges.
The underdog finished the stronger, but several stanzas were difficult to score. However, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor advances, but with the caliber of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Hatton Homage Motivates All-Manchester Battle
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a outstanding Manchester vs Manchester battle to capture the continental title.
The arena became quiet for a deeply poignant tribute before the fight as a bell ceremony rang in memory of Manchester's own Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the last bell ended, the stillness became a shout of "only one Hatton".
The fighting inside the ropes matched the sentiment. The eventual winner was floored by a significant blow squarely on the jaw in the second round, rising shakily to his feet on the referee's count.
But the Manchester United-red equipment of the fighter soon advanced again. Across the ring, Rea - in rival City blue - was injured early, noticeable damage appearing under his eye as the duo traded punishing blows.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with powerful upward punches as the pace seldom decreased over twelve rounds.
Arthur narrowly won the decision with official scores of 114-114, narrow lead and wider gap, but both fighters were determined and brave, exactly what their idol Hatton stood for.
