UK light-heavyweight Buatsi made a winning yet unimpressive beginning to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a close 10-round fight at the boxing arena.
But the challenger had his moments, delivering effective single shots in a match where the approaches didn't complement each other, with frequent clinching disrupting the action.
Two judges had it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but how do champions respond? They succeed," Buatsi said in the arena as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Some ringside observers believed the challenger, thirty-one, merited the win but the contender experienced the second defeat of his 28-bout professional journey.
The Champion Secures Triumph in Dull Encounter
His career development has stalled in recent times through contract problems and long spells of inactivity.
Once tipped as the rising talent of the British fight scene, he now is positioned trying to realize his potential - possibly in what feels like a last chance - under fresh management.
He opened tentatively, with neither fighter willing to overcommit in a cagey opening few rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second fight at the higher weight class.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who worked behind a tight guard to edge the cleaner rounds.
The spectators' acceptance diminished during constant clinching, with the challenger falling to the floor several times during close exchanges.
The underdog finished the stronger, but multiple periods were hard to judge. However, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a outstanding Manchester vs Manchester contest to capture the European light-heavyweight belt.
The stadium became quiet for a deeply poignant memorial prior to the bout as ten bells sounded in honor of Manchester's own Hatton, who died 46 years old in recently.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the final chime ended, the quiet transitioned to a roar of "only one Ricky Hatton".
The competition inside the ropes reflected the sentiment. The eventual winner was sent to the canvas by a powerful punch flush on the face in the early round, standing uncertainly to his position on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, the opponent - in competitive blue - was damaged quickly, significant bruising developing under his orbital area as the duo exchanged powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with effective uppercuts as the intensity seldom decreased over twelve rounds.
Arthur barely secured the decision with official scores of even score, narrow lead and wider gap, but each competitor were relentless and brave, everything their hero the legend embodied.
