UK light-heavyweight Buatsi made a winning yet underwhelming debut to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a competitive ten-round bout at the boxing arena.
But the challenger found success, connecting with powerful single shots in a match where the approaches never quite clicked, with frequent clinching marring the contest.
Two judges judged it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my finest display but how do champions respond? They win," Buatsi commented in the ring as he was faced disapproval from the audience.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Several boxing experts believed the challenger, 31, deserved the win but the British boxer endured the second loss of his 28-match career.
The Champion Earns Triumph in Uneventful Affair
Buatsi's progress has plateaued in the past few years through contract problems and considerable time of inactivity.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to achieve expectations - possibly in what feels like a final roll of the dice - under fresh management.
He started carefully, with both competitors ready to take risks in a calculated initial rounds.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was participating in his second appearance at light heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for the favorite, who utilized a solid defense to barely take the better periods.
The audience's tolerance wore thin because of frequent holding, with the challenger slipping to the canvas multiple occasions during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. Although, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Motivates All-Manchester Fight
In the co-main event, Lyndon Arthur beat Bradley Rea by close verdict in a outstanding all-Manchester contest to win the European light heavyweight belt.
The stadium grew hushed for a extremely emotional homage prior to the bout as a bell ceremony tolled in memory of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the premier televised boxing event in the urban center since Hatton's death. As the final chime ended, the stillness transitioned to a chant of "there's only one Hatton".
The action inside the ropes reflected the sentiment. Arthur was sent to the canvas by a powerful punch directly to the chin in the second round, getting up unsteadily to his footing on the count of eight.
But the traditional red attire of Arthur soon came forward again. From the other corner, the opponent - in competitive blue - was damaged early, significant bruising appearing under his orbital area as the fighters exchanged powerful shots.
Rea, twenty-seven, connected with strong blows but Arthur, 34, fought fire with fire with stinging uppercuts as the pace hardly diminished over 12 rounds.
Arthur barely secured the decision with official scores of even score, 115-113 and clearer margin, but each competitor were relentless and brave, all the qualities their inspiration the legend embodied.
