UK light heavyweight Buatsi secured a victory yet underwhelming debut to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a majority decision in a tight 10-round fight at the Manchester venue.
But Parker landed significant shots, landing some telling single shots in a fight where the approaches didn't complement each other, with constant grabbing spoiling the action.
Two judges scored it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest display but what defines champions? They succeed," the victor commented in the ringside as he was greeted with disapproval from the spectators.
The British fighter bounced back after his maiden career setback - an memorable fight with his previous opponent in February - to secure a twentieth professional win.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the Derbyshire fighter suffered the second defeat of his 28-match career.
The Champion Earns Victory in Uneventful Match
The fighter's advancement has plateaued in recent years through promotional disputes and considerable time of inactivity.
Previously predicted as the rising talent of British boxing, he now stands trying to fulfil that early promise - possibly in what appears to be a last chance - under fresh management.
He started carefully, with the two boxers willing to take risks in a calculated opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was participating in his second bout at the higher weight class.
By the halfway stage, Parker had kept it close, creating difficulties for the favorite, who operated with a protective stance to barely take the better periods.
The crowd's patience decreased amid constant clinching, with the challenger going down several times during clinches.
Parker finished the stronger, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, awarding Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Homage Inspires Local Rivalry Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding all-Manchester fight to win the European light-heavyweight championship.
The arena grew hushed for a profoundly moving tribute prior to the bout as 10 bells sounded in remembrance of local hero Ricky Hatton, who died aged 46 in recently.
It was the premier televised match card in the location since the passing of Hatton. As the last bell ended, the silence transitioned to a chant of "there's just one Ricky Hatton".
The fighting inside the ropes matched the sentiment. Arthur was sent to the canvas by a left hook flush on the jaw in the second round, standing uncertainly to his position on the eight count.
But the red-colored equipment of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was marked up quickly, heavy swelling developing under his eye as the fighters exchanged powerful shots.
Rea, 27, landed power punches but the champion, 34, responded in kind with stinging uppercuts as the action hardly diminished over 12 rounds.
The victor edged the verdict with judges scorecards of even score, 115-113 and clearer margin, but the two athletes were relentless and full of heart, all the qualities their idol Hatton stood for.
