UK light heavyweight Buatsi earned a win yet underwhelming debut to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a close ten-round bout at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling clean blows in a match where the techniques failed to mesh, with frequent clinching spoiling the contest.
Two judges judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my best performance but what do champions do? They succeed," the victor said in the ringside as he was greeted with negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts felt the challenger, 31, deserved the decision but the British boxer endured the second setback of his 28-match career.
The Champion Earns Triumph in Slow Match
His career development has slowed in recent years through management issues and considerable time of inactivity.
Previously predicted as the rising talent of British boxing, he now stands trying to achieve expectations - maybe in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter willing to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after breaking his hand during the bout, was making just his second appearance at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who operated with a tight guard to barely take the better periods.
The spectators' acceptance wore thin during constant clinching, with the challenger going down multiple occasions during close exchanges.
Parker finished the stronger, but many rounds were challenging to assess. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still seems difficult.
Hatton Homage Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Rea by split-decision in a excellent all-Manchester battle to secure the European light-heavyweight belt.
The venue fell silent for a profoundly moving tribute ahead of the contest as 10 bells tolled in honor of Manchester's own Ricky Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast match card in the urban center since Hatton's passing. As the last bell ended, the stillness transitioned to a shout of "there's only one Ricky Hatton".
The action within the ring equaled the emotion. Arthur was sent to the canvas by a powerful punch squarely on the face in the initial stage, rising shakily to his footing on the eight count.
But the traditional red attire of Arthur soon advanced again. Across the ring, the opponent - in rival City blue - was damaged soon, heavy swelling forming under his orbital area as the duo traded punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with stinging uppercuts as the action seldom decreased over twelve rounds.
The victor narrowly won the decision with scoring tallies of even score, close margin and wider gap, but each competitor were determined and brave, all the qualities their hero Hatton represented.
