UK light-heavyweight Buatsi secured a victory yet unimpressive beginning to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a split decision in a competitive 10-round bout at the Manchester venue.
But the challenger found success, landing some telling single shots in a match where the approaches failed to mesh, with constant grabbing marring the fight.
Two judges judged it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my finest showing but what defines champions? They prevail," Buatsi stated in the arena as he was faced boos from the audience.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the win but the British boxer endured the second defeat of his 28-bout professional journey.
The Champion Earns Win in Slow Encounter
Buatsi's progress has slowed in recent times through management issues and extended periods of lack of fights.
Previously predicted as the future of British boxing, he now is positioned trying to achieve expectations - possibly in what appears to be a final roll of the dice - under recent support.
He began cautiously, with neither fighter prepared to overcommit in a cagey 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 participating in his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to edge the better stanzas.
The spectators' acceptance diminished amid regular grabbing, with the challenger slipping to the canvas various instances during grappling.
Parker ended stronger, but many rounds were hard to judge. Although, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Inspires Local Rivalry Battle
In the co-main event, Lyndon Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester fight to secure the European light-heavyweight belt.
The arena grew hushed for a deeply poignant homage before the fight as 10 bells sounded in honor of local hero Hatton, who passed away 46 years old in recently.
It was the premier televised fight night in the location since the passing of Hatton. As the final chime faded, the stillness became a roar of "there's only one Hatton".
The competition within the ring equaled the sentiment. Arthur was sent to the canvas by a left hook directly to the chin in the early round, getting up unsteadily to his footing on the eight count.
But the red-colored equipment of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was marked up early, noticeable damage developing under his face as the duo landed hard punches.
Rea, 27, connected with strong blows but the champion, thirty-four, responded in kind with powerful upward punches as the intensity hardly diminished over 12 rounds.
Arthur edged the verdict with judges scorecards of draw, 115-113 and wider gap, but both fighters were persistent and brave, everything their hero the legend stood for.
