UK light heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a close ten-round fight at the Manchester venue.
But the challenger had his moments, connecting with powerful single shots in a fight where the techniques never quite clicked, with frequent clinching spoiling the fight.
The scoring judges scored it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best performance but what do champions do? They succeed," Buatsi commented in the ring as he was greeted with negative reactions from the crowd.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, deserved the victory but the contender experienced the second defeat of his 28-match professional journey.
Buatsi Claims Win in Slow Match
The fighter's advancement has stalled in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under recent support.
He began cautiously, with the two boxers prepared to take risks in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who operated with a protective stance to barely take the cleaner periods.
The audience's tolerance decreased amid frequent holding, with Parker falling to the floor multiple occasions during clinches.
The underdog closed well, but several stanzas were challenging to assess. However, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the likes of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Battle
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a outstanding local rivalry contest to capture the European light heavyweight belt.
The venue grew hushed for a deeply poignant memorial ahead of the contest as 10 bells tolled in memory of local hero Hatton, who passed away at age 46 in September.
It was the premier televised fight night in the location since Hatton's death. As the final chime disappeared, the silence became a shout of "there's just one Hatton".
The action within the ring matched the sentiment. The eventual winner was sent to the canvas by a left hook squarely on the chin in the initial stage, rising shakily to his position on the referee's count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. Across the ring, Rea - in rival City blue - was damaged early, noticeable damage forming under his face as the pair exchanged hard punches.
Rea, 27, landed power punches but the champion, 34, responded in kind with powerful upward punches as the pace hardly diminished over the full distance.
Arthur barely secured the result with official scores of even score, close margin and 115-112, but the two athletes were persistent and courageous, exactly what their idol the legend represented.
