British light-heavyweight Buatsi made a winning yet unimpressive beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a split decision in a competitive ten-round bout at the Co-op Live Arena.
But Parker found success, landing some telling individual punches in a contest where the styles didn't complement each other, with constant grabbing disrupting the fight.
The scoring judges had it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my best display but what do champions do? They prevail," the victor commented in the ring as he was met by boos from the crowd.
The British fighter returned to winning ways after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a 20th pro success.
Various analysts thought Parker, thirty-one, merited the victory but the British boxer endured the second defeat of his 28-fight professional journey.
Buatsi Claims Win in Slow Affair
Buatsi's progress has stalled in recent times through management issues and extended periods of lack of fights.
Once tipped as the future of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what seems like a final roll of the dice - under new promotional backing.
He started carefully, with both competitors willing to be aggressive in a tentative initial rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had kept it close, making life awkward for the favorite, who operated with a protective stance to barely take the cleaner periods.
The audience's tolerance wore thin because of regular grabbing, with the challenger slipping to the canvas various instances during grappling.
Parker closed well, but many rounds were hard to judge. Although, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for the challenger, giving Buatsi just a single round.
Buatsi advances, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Homage Inspires Manchester Derby Contest
In the secondary fight, Lyndon Arthur beat Rea by split-decision in a excellent local rivalry fight to secure the continental belt.
The stadium grew hushed for a extremely emotional tribute prior to the bout as ten bells sounded in memory of local hero Ricky Hatton, who succumbed at age 46 in recently.
It was the first major televised fight night in the urban center since the passing of Hatton. As the final chime faded, the quiet became a shout of "there's just one Ricky Hatton".
The competition within the ring matched the emotion. The eventual winner was floored by a left hook flush on the face in the second round, getting up unsteadily to his feet on the eight count.
But the red-colored attire of the fighter soon came forward again. On the opposite side, the opponent - in competitive blue - was marked up early, noticeable damage forming under his face as the duo exchanged hard punches.
Rea, 27, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the action seldom decreased over the full distance.
The victor barely secured the result with judges scorecards of 114-114, 115-113 and 115-112, but each competitor were determined and brave, all the qualities their inspiration Hatton embodied.
