Muhammed Lawal wasn't playing around this time.
Lawal (10-2) scored an early takedown in the first round of the light heavyweight tournament fight and, from a standing position in Petruzelli's guard, unleashed a winging right hand to the chin for a highlight knockout finish.
The victory, which took just 95 seconds, sends Lawal to the Bellator tournament finals against Jacob Noe later this year and hopefully begins to erase the embarrassing knockout he suffered at the hands of Emanuel Newton in February.
After taking criticism for keeping his hands perilously low in that fight, Lawal was all business against Petruzelli (14-8). The 32-year-old didn't so much as smile the entire night, even as the result of the bout was announced at the WinStar World Casino.
The main event got off to a bizarre start when Petruzelli apparently injured his eye on a grazing head butt by Lawal during a takedown attempt. Petruzelli sprawled, was clipped by Lawal's head and covered up in the center of the cage.
Referee John McCarthy stopped the action and gave Petruzelli time to recover. Lawal's takedown came shortly after the fight resumed.
Petruzelli falls to 1-2 in the Bellator cage. He suffered a first-round TKO loss to Noe at Bellator 85 earlier this year. Lawal, a former title holder at 205 pounds in Strikeforce, recorded the eighth knockout of his pro career.
Babalu retires after stoppage loss
It's not often a fight is stopped while two fighters are on opposite ends of the cage.
That was the case in the opening round of the Bellator light heavyweight tournament, when Renato "Babalu" Sobral suffered a third-round TKO loss to Jacob Noe, despite being about 15 feet away from him at the time of the stoppage.
Virtually out on his feet from punches, Sobral turned his back and ran away from Noe in the final minutes of the bout, prompting referee Kerry Hatley to wave off the action at the 3:32 mark.
Sobral (37-11) protested, even shoving Hatley at one point, but it was an acceptable stoppage. Afterward, Sobral, 37, announced his retirement from martial arts, ending a career that began in 1997.
The Brazilian's biggest issue was his inability to even come close to getting Noe (12-2) on the ground. He went 0-4 on takedown attempts in the first round and absorbed a steady dose of lead left hooks by Noe.
Sobral tried to change the course of the fight in the second round, leading with his jab and opening a cut on the bridge of his opponent's nose. He continued to eat left hooks though, a theme that would continue in the final round.
One final desperate takedown attempt by Sobral was the beginning of the end. Sensing Sobral's gas tank was low, Noe battered him with right hands until the fight was stopped.
Noe improved to 3-1 under the Bellator banner. He'll meet Lawal to close out the promotion's four-man tournament later this summer.
Minakov makes quick work of Sparks
Anything can happen in martial arts -- including, occasionally, exactly what's expected.
Minakov met his opponent at the center of the cage from the opening bell. Sparks, in an effort to start a brawl, managed a few swing-and-misses but was quickly blasted by a Minakov right hand.
Referee John McCarthy gave Sparks a moment to recover, but when the Kentucky-based heavyweight rolled to his stomach and covered up, this one was over.
Minakov (11-0) has finished all but one of his professional bouts. This was his sixth career knockout victory. Sparks (8-2) has now been finished in the first round in back-to-back appearances.
War Machine blasts through Avena
War Machine has finally made his Bellator debut -- and it was a good one.
Born Jon Koppenhaver, "War Machine" signed with Bellator in 2011 and was scheduled to compete in two of the promotion's previous tournaments, but a one-year jail sentence and torn ACL injury prevented him from competition until now.
The 31-year-old wasted no time in his first Bellator appearance, securing multiple takedowns on Blas Avena and eventually transitioning to a full crucifix. A series of left hands and elbows forced referee Kerry Hatley to stop the fight at the 3:55 mark, handing War Machine a first-round TKO victory.
"I'm here man, I'm coming," War Machine said. "I want that belt. I'm coming and I'm going to hurt some people."
Sticking to his notoriously aggressive style, War Machine (13-4) walked Avena down in the opening minutes of the fight with combinations of left hooks and right crosses. He took Avena (8-7) down early and scored several hard right hands as Avena wall-walked back to his feet.
Following a few exchanges in the clinch, War Machine landed his second takedown of the fight midway through the round, which led to the finish. It's his first win since November 2011.