British light-heavyweight Buatsi made a winning yet unimpressive beginning to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a competitive 10-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful single shots in a match where the approaches didn't complement each other, with frequent clinching spoiling the fight.
The officials judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my finest display but what defines champions? They succeed," the victor said in the arena as he was greeted with negative reactions from the crowd.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Various analysts thought Parker, 31, should have been awarded the decision but the contender endured the second setback of his 28-bout professional journey.
The Champion Secures Triumph in Uneventful Match
His career development has slowed in the past few years through promotional disputes and extended periods of inactivity.
Previously predicted as the next star of the British fight scene, he now is positioned trying to realize his potential - maybe in what seems like a last chance - under recent support.
He started carefully, with the two boxers ready to overcommit in a tentative opening few rounds.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after suffering a hand injury in the contest, was making just his second appearance at the higher weight class.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who utilized a solid defense to edge the better stanzas.
The audience's tolerance diminished amid constant clinching, with the challenger going down various instances during grappling.
The underdog closed well, but multiple periods were hard to judge. However, previous titleholder the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, giving Buatsi just only one stanza.
The victor advances, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Contest
In the secondary fight, Arthur defeated Rea by close verdict in a excellent Manchester vs Manchester contest to secure the European light-heavyweight belt.
The arena became quiet for a deeply poignant homage before the fight as ten bells rang in remembrance of Manchester's own Hatton, who succumbed aged 46 in recently.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the final chime faded, the stillness transitioned to a roar of "there's only one Ricky Hatton".
The action within the ring reflected the sentiment. Arthur was knocked down by a significant blow directly to the chin in the early round, standing uncertainly to his position on the referee's count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, Rea - in competitive blue - was marked up early, significant bruising forming under his orbital area as the duo traded punishing blows.
Rea, 27, delivered effective strikes but Arthur, thirty-four, responded in kind with stinging uppercuts as the intensity seldom decreased over 12 rounds.
The victor barely secured the verdict with official scores of even score, close margin and 115-112, but each competitor were determined and full of heart, all the qualities their hero the legend embodied.
