UK light-heavyweight Buatsi secured a victory yet unimpressive start to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a competitive ten-round contest at the Manchester venue.
But Parker found success, delivering effective clean blows in a fight where the techniques failed to mesh, with excessive holding disrupting the action.
The officials scored it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best performance but how do champions respond? They win," the victor commented in the ring as he was faced negative reactions from the spectators.
The Londoner got back to winning after his first professional defeat - an memorable fight with his previous opponent in February - to earn a 20th career victory.
Several boxing experts felt the challenger, 31, should have been awarded the decision but the British boxer suffered the second loss of his 28-bout professional journey.
Buatsi Claims Triumph in Slow Affair
Buatsi's progress has slowed in recent times through management issues and long spells of lack of fights.
Earlier forecast as the next star of UK boxing, he now finds himself trying to achieve expectations - maybe in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with both competitors ready to overcommit in a calculated opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for Buatsi, who worked behind a solid defense to narrowly win the better rounds.
The audience's tolerance diminished during constant clinching, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog closed well, but many rounds were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor progresses, but with the likes of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Hatton Memorial Fuels Manchester Derby Battle
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a excellent all-Manchester fight to capture the European light-heavyweight belt.
The stadium grew hushed for a deeply poignant homage ahead of the contest as a bell ceremony rang in honor of Manchester's own Ricky Hatton, who succumbed 46 years old in recently.
It was the premier televised match card in the urban center since the passing of Hatton. As the last bell ended, the stillness gave way to a roar of "there's only one Hatton".
The action within the ring equaled the sentiment. The eventual winner was knocked down by a significant blow flush on the chin in the initial stage, rising shakily to his feet on the count of eight.
But the red-colored attire of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was damaged early, significant bruising forming under his orbital area as the duo exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the intensity rarely dropped over twelve rounds.
The victor edged the result with scoring tallies of 114-114, close margin and 115-112, but the two athletes were relentless and brave, exactly what their idol the legend embodied.
