British light heavyweight Buatsi made a winning yet underwhelming start to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a split decision in a competitive 10-round contest at the boxing arena.
But Parker found success, landing some telling single shots in a fight where the styles failed to mesh, with frequent clinching disrupting the action.
Two judges judged it 96-94 for to the winner, with the final judge a even score.
"It wasn't my best performance but what defines champions? They prevail," Buatsi stated in the ringside as he was faced negative reactions from the crowd.
The British fighter bounced back after his first professional defeat - an thrilling contest with Callum Smith in last winter - to secure a 20th pro success.
Some ringside observers thought Parker, 31, merited the win but the contender endured the second defeat of his 28-bout professional journey.
The Champion Earns Victory in Slow Encounter
His career development has slowed in recent times through promotional disputes and considerable time of inactivity.
Earlier forecast as the future of the British fight scene, he now stands trying to fulfil that early promise - maybe in what seems like a final roll of the dice - under fresh management.
He started carefully, with both competitors prepared to be aggressive in a calculated initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for the favorite, who utilized a protective stance to barely take the better periods.
The spectators' acceptance diminished because of regular grabbing, with the challenger going down various instances during grappling.
Parker finished the stronger, but several stanzas were hard to judge. Nevertheless, ex-champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of hard hitter Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the secondary fight, Lyndon Arthur defeated Bradley Rea by close verdict in a terrific Manchester vs Manchester fight to capture the continental belt.
The arena grew hushed for a extremely emotional tribute prior to the bout as 10 bells tolled in honor of Manchester's own Ricky Hatton, who passed away aged 46 in last month.
It was the premier televised match card in the urban center since the passing of Hatton. As the concluding sound faded, the silence became a roar of "there's just one Ricky Hatton".
The fighting inside the ropes matched the emotion. The eventual winner was knocked down by a powerful punch flush on the jaw in the initial stage, getting up unsteadily to his footing on the referee's count.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was injured early, noticeable damage appearing under his eye as the fighters traded powerful shots.
Rea, 27, connected with strong blows but the champion, thirty-four, responded in kind with stinging uppercuts as the intensity rarely dropped over 12 rounds.
The victor barely secured the result with official scores of draw, narrow lead and 115-112, but both fighters were relentless and full of heart, everything their idol Hatton embodied.
