UK light heavyweight Buatsi earned a win yet disappointing start to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close ten-round contest at the Co-op Live Arena.
But the challenger found success, delivering effective single shots in a fight where the approaches never quite clicked, with frequent clinching marring the contest.
Two judges scored it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my greatest display but what defines champions? They succeed," Buatsi stated in the arena as he was faced negative reactions from the audience.
The Londoner got back to winning after his maiden career setback - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Several boxing experts thought the challenger, thirty-one, should have been awarded the victory but the contender suffered the second defeat of his 28-match professional journey.
Buatsi Secures Triumph in Slow Match
Buatsi's progress has plateaued in recent times through management issues and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now stands trying to realize his potential - possibly in what feels like a last chance - under fresh management.
He opened tentatively, with the two boxers ready to be aggressive in a tentative opening few rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was making just his second bout at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for the favorite, who worked behind a tight guard to barely take the more effective rounds.
The spectators' acceptance diminished during regular grabbing, with the challenger falling to the floor multiple occasions during grappling.
The underdog closed well, but many rounds were challenging to assess. However, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for the challenger, awarding Buatsi just a single round.
Buatsi advances, but with the presence of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Tribute Motivates Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Rea by close verdict in a excellent local rivalry fight to win the European light-heavyweight belt.
The arena became quiet for a deeply poignant tribute before the fight as 10 bells sounded in memory of Manchester's own Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the last bell faded, the stillness became a shout of "there's only one Ricky Hatton".
The action inside the ropes matched the sentiment. The eventual winner was floored by a left hook directly to the face in the second round, standing uncertainly to his footing on the eight count.
But the red-colored equipment of the fighter soon came forward again. From the other corner, the opponent - in opposing blue - was damaged quickly, noticeable damage appearing under his orbital area as the duo traded punishing blows.
The challenger, 27, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the intensity rarely dropped over the full distance.
The victor narrowly won the verdict with scoring tallies of 114-114, 115-113 and clearer margin, but each competitor were persistent and brave, everything their hero the legend stood for.
