British light heavyweight Buatsi made a winning yet disappointing start to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a competitive 10-round bout at the Manchester venue.
But Parker had his moments, landing some telling clean blows in a match where the techniques never quite clicked, with excessive holding marring the fight.
Two judges had it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my finest showing but what defines champions? They win," Buatsi commented in the ring as he was met by negative reactions from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers believed the challenger, thirty-one, should have been awarded the victory but the British boxer experienced the second defeat of his 28-match professional journey.
Buatsi Earns Victory in Uneventful Match
Buatsi's progress has slowed in recent times through contract problems and considerable time of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to fulfil that early promise - possibly in what seems like a ultimate opportunity - under recent support.
He started carefully, with the two boxers ready to overcommit in a cagey opening few rounds.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for Buatsi, who worked behind a tight guard to narrowly win the cleaner stanzas.
The audience's tolerance diminished during regular grabbing, with the challenger falling to the floor several times during close exchanges.
Parker closed well, but several stanzas were hard to judge. Nevertheless, previous titleholder the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian star Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires All-Manchester Fight
In the secondary fight, Arthur defeated Bradley Rea by close verdict in a terrific Manchester vs Manchester battle to secure the European light heavyweight title.
The stadium fell silent for a extremely emotional tribute prior to the bout as 10 bells sounded in memory of the city's native Ricky Hatton, who died aged 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the final chime ended, the silence gave way to a chant of "there's only one Ricky Hatton".
The competition during the bout reflected the sentiment. Arthur was knocked down by a significant blow squarely on the jaw in the initial stage, rising shakily to his feet on the count of eight.
But the red-colored shorts of the fighter soon advanced again. From the other corner, Rea - in opposing blue - was injured soon, significant bruising appearing under his eye as the fighters exchanged punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity rarely dropped over twelve rounds.
Arthur narrowly won the decision with scoring tallies of even score, close margin and clearer margin, but both fighters were relentless and brave, everything their hero the legend represented.
