British light heavyweight Buatsi secured a victory yet disappointing start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a close ten-round fight at the Manchester venue.
But Parker found success, connecting with powerful single shots in a contest where the techniques never quite clicked, with frequent clinching disrupting the action.
The scoring judges had it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my finest performance but what defines champions? They succeed," the victor said in the arena as he was faced boos from the spectators.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Various analysts believed the challenger, thirty-one, deserved the decision but the Derbyshire fighter suffered the second setback of his 28-fight professional journey.
The Champion Earns Victory in Dull Encounter
His career development has stalled in recent years through promotional disputes and long spells of inactivity.
Earlier forecast as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with the two boxers willing to take risks in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in two years ago after breaking his hand mid-fight, was competing in only his second bout at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who utilized a protective stance to narrowly win the better stanzas.
The audience's tolerance decreased because of frequent holding, with Parker slipping to the canvas multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were hard to judge. Nevertheless, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Hatton Homage Motivates All-Manchester Battle
In the co-main event, Arthur beat Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to secure the European light-heavyweight belt.
The stadium became quiet for a extremely emotional memorial before the fight as ten bells rang in honor of the city's native Ricky Hatton, who died aged 46 in recently.
It was the premier televised boxing event in the urban center since Hatton's death. As the final chime disappeared, the quiet became a shout of "there's just one Ricky Hatton".
The fighting inside the ropes matched the emotion. Arthur was knocked down by a powerful punch directly to the chin in the initial stage, standing uncertainly to his position on the referee's count.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, Rea - in competitive blue - was marked up quickly, significant bruising appearing under his orbital area as the fighters landed hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over 12 rounds.
The victor barely secured the result with scoring tallies of even score, 115-113 and wider gap, but the two athletes were determined and brave, everything their idol Hatton embodied.
