British light heavyweight Buatsi made a winning yet unimpressive beginning to his career under fresh promotional backing with a unanimous decision 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 bout at the Manchester venue.
But Parker found success, landing some telling individual punches in a fight where the techniques never quite clicked, with constant grabbing spoiling the fight.
The officials scored it 96-94 for to the winner, with the final judge a even score.
"It wasn't my best showing but what defines champions? They win," Buatsi commented in the ringside as he was faced boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to secure a twentieth professional win.
Some ringside observers believed Parker, thirty-one, merited the win but the Derbyshire fighter endured the second defeat of his 28-match career.
The Champion Earns Victory in Slow Affair
The fighter's advancement has slowed in recent years through management issues and long spells of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to achieve expectations - possibly in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter prepared to take risks in a cagey early stages.
The challenger, whose only previous defeat 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 fight at light-heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for Buatsi, who utilized a solid defense to narrowly win the cleaner rounds.
The crowd's patience diminished during regular grabbing, with the challenger slipping to the canvas various instances during close exchanges.
Parker ended stronger, but multiple periods were hard to judge. However, previous titleholder Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the likes of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Contest
In the co-main event, Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester fight to secure the European light-heavyweight belt.
The stadium became quiet for a profoundly moving tribute ahead of the contest as ten bells tolled in remembrance of Manchester's own Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the last bell disappeared, the silence became a roar of "only one Ricky Hatton".
The action within the ring matched the sentiment. The eventual winner was sent to the canvas by a powerful punch flush on the jaw in the second round, rising shakily to his feet on the count of eight.
But the traditional red shorts of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was marked up quickly, significant bruising appearing under his orbital area as the fighters traded punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, responded in kind with effective uppercuts as the intensity rarely dropped over 12 rounds.
The victor barely secured the result with scoring tallies of 114-114, 115-113 and clearer margin, but the two athletes were determined and brave, all the qualities their idol the legend represented.
