British light-heavyweight Buatsi made a winning yet underwhelming start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a split decision in a competitive ten-round contest at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling individual punches in a contest where the styles failed to mesh, with constant grabbing disrupting the action.
The officials judged it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my finest performance but what do champions do? They win," Buatsi stated in the ring as he was faced negative reactions from the audience.
The Londoner got back to winning after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers felt the challenger, thirty-one, merited the decision but the contender endured the second loss of his 28-bout professional journey.
The Champion Secures Triumph in Uneventful Affair
The fighter's advancement has slowed in recent times through management issues and considerable time of inactivity.
Once tipped as the rising talent of the British fight scene, he now stands trying to realize his potential - possibly in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with neither fighter willing to be aggressive in a calculated early stages.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand in the contest, was competing in only his second fight at light heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for Buatsi, who worked behind a tight guard to narrowly win the better stanzas.
The crowd's patience decreased amid frequent holding, with the challenger falling to the floor several times during close exchanges.
The underdog closed well, but multiple periods were difficult to score. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Homage Inspires Manchester Derby Fight
In the secondary fight, Arthur beat Rea by close verdict in a terrific all-Manchester battle to capture the continental championship.
The stadium became quiet for a profoundly moving homage prior to the bout as a bell ceremony rang in honor of the city's native Ricky Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the location since Hatton's death. As the last bell disappeared, the quiet transitioned to a shout of "there's only one Hatton".
The competition within the ring reflected the emotion. Arthur was knocked down by a powerful punch squarely on the jaw in the initial stage, getting up unsteadily to his footing on the count of eight.
But the traditional red shorts of the fighter soon came forward again. From the other corner, the opponent - in competitive blue - was damaged early, heavy swelling developing under his orbital area as the pair landed hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, responded in kind with powerful upward punches as the action hardly diminished over the full distance.
Arthur narrowly won the decision with judges scorecards of draw, narrow lead and clearer margin, but each competitor were persistent and brave, all the qualities their hero Hatton embodied.
