British light heavyweight Buatsi earned a win yet disappointing beginning to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a tight 10-round contest at the boxing arena.
But the challenger landed significant shots, connecting with powerful clean blows in a fight where the styles didn't complement each other, with frequent clinching marring the contest.
The scoring judges had it 96-94 to Buatsi, with the final judge a 95-95.
"It wasn't my finest showing but what defines champions? They prevail," Buatsi stated in the arena as he was met by negative reactions from the audience.
The British fighter got back to winning after his first professional defeat - an thrilling contest with Callum Smith in last winter - to claim a 20th pro success.
Some ringside observers felt the challenger, 31, should have been awarded the decision but the British boxer experienced the second loss of his 28-bout career.
Buatsi Secures Win in Dull Match
His career development has plateaued in recent years through promotional disputes and considerable time of lack of fights.
Previously predicted as the rising talent of British boxing, he now stands trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He began cautiously, with the two boxers willing to overcommit in a calculated initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was making just his second fight at light heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for Buatsi, who operated with a protective stance to edge the better stanzas.
The audience's tolerance diminished amid frequent holding, with Parker slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. Nevertheless, previous titleholder Carl Frampton - working with the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Memorial Fuels Local Rivalry Contest
In the supporting bout, Arthur overcame Rea by divided decision in a outstanding Manchester vs Manchester fight to secure the European light heavyweight title.
The venue grew hushed for a profoundly moving homage before the fight as 10 bells rang in remembrance of the city's native Ricky Hatton, who passed away 46 years old in September.
It was the premier televised boxing event in the location since the passing of Hatton. As the final chime disappeared, the silence became a shout of "there's just one Hatton".
The fighting inside the ropes reflected the feeling. Arthur was floored by a left hook flush on the chin in the second round, rising shakily to his position on the count of eight.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, the opponent - in competitive blue - was injured quickly, noticeable damage developing under his face as the duo landed punishing blows.
The challenger, 27, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the action rarely dropped over 12 rounds.
The victor edged the result with official scores of 114-114, 115-113 and wider gap, but the two athletes were persistent and full of heart, exactly what their inspiration Hatton embodied.
