UK light heavyweight Buatsi earned a win yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight 10-round bout at the boxing arena.
But Parker found success, connecting with powerful single shots in a match where the approaches didn't complement each other, with frequent clinching disrupting the action.
The scoring judges scored it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi said in the ring as he was faced negative reactions from the audience.
The British fighter bounced back after his maiden career setback - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Various analysts believed the challenger, 31, deserved the win but the Derbyshire fighter suffered the second loss of his 28-match career.
The Champion Earns Triumph in Dull Match
His career development has slowed in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to realize his potential - perhaps in what seems like a last chance - under recent support.
He opened tentatively, with the two boxers prepared to overcommit in a tentative opening few rounds.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second fight at the higher weight class.
By the halfway stage, Parker had kept it close, causing problems for Buatsi, who utilized a protective stance to narrowly win the better rounds.
The crowd's patience diminished amid constant clinching, with Parker falling to the floor various instances during close exchanges.
Parker finished the stronger, but multiple periods were challenging to assess. Although, ex-champion the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor advances, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Fuels All-Manchester Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent all-Manchester fight to win the European light-heavyweight championship.
The stadium became quiet for a profoundly moving tribute ahead of the contest as ten bells tolled in honor of the city's native Hatton, who succumbed aged 46 in recently.
It was the premier televised match card in the city since Hatton's passing. As the last bell disappeared, the stillness gave way to a shout of "there's just one Hatton".
The fighting during the bout reflected the sentiment. Arthur was knocked down by a left hook squarely on the jaw in the second round, standing uncertainly to his position on the eight count.
But the red-colored attire of the fighter soon came forward again. From the other corner, Rea - in competitive blue - was damaged early, heavy swelling developing under his orbital area as the duo exchanged punishing blows.
The challenger, 27, connected with strong blows but the champion, thirty-four, responded in kind with effective uppercuts as the intensity hardly diminished over 12 rounds.
The victor barely secured the verdict with scoring tallies of draw, 115-113 and clearer margin, but the two athletes were determined and courageous, exactly what their idol Hatton represented.
