British light-heavyweight Buatsi earned a win yet disappointing beginning to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a tight ten-round contest at the Manchester venue.
But the challenger found success, connecting with powerful individual punches in a match where the styles never quite clicked, with frequent clinching disrupting the fight.
Two judges scored it 96-94 in favor to the winner, with the remaining official a even score.
"It wasn't my best display but how do champions respond? They prevail," Buatsi said in the ringside as he was faced boos from the spectators.
The British fighter bounced back after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts felt Parker, 31, merited the win but the contender experienced the second defeat of his 28-match career.
The Champion Secures Victory in Uneventful Affair
His career development has stalled in recent times through management issues and extended periods of lack of fights.
Earlier forecast as the next star of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with the two boxers willing to overcommit in a calculated early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after damaging his hand in the contest, was making just his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who operated with a protective stance to narrowly win the cleaner stanzas.
The spectators' acceptance diminished amid regular grabbing, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog finished the stronger, but several stanzas were challenging to assess. However, previous titleholder the boxing analyst - working with the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Memorial Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur defeated Rea by close verdict in a outstanding local rivalry fight to win the continental belt.
The venue fell silent for a deeply poignant memorial prior to the bout as a bell ceremony tolled in memory of local hero Ricky Hatton, who succumbed at age 46 in September.
It was the first major televised match card in the city since Hatton's passing. As the final chime ended, the stillness became a roar of "there's just one Hatton".
The fighting inside the ropes matched the sentiment. The eventual winner was floored by a powerful punch flush on the chin in the early round, getting up unsteadily to his feet on the eight count.
But the Manchester United-red equipment of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was injured quickly, noticeable damage forming under his eye as the pair landed punishing blows.
Rea, 27, landed power punches but the champion, thirty-four, matched the intensity with stinging uppercuts as the pace seldom decreased over twelve rounds.
The victor edged the result with scoring tallies of draw, close margin and 115-112, but the two athletes were relentless and full of heart, exactly what their hero Hatton represented.
