The fight had been mostly even until midway through the second round, when Gustafsson unleashed a sensational combination: He swung and missed with an uppercut, then threw a left head kick followed by a right front kick, connected with a big left hand to the chin, landed two right uppercuts to knock Hamill down, then pounced on Hamill on the ground and landed brutal punches and elbows on the ground, forcing referee Dan Miragliotta to stop the fight.
The victory was the biggest of Gustafsson's career, and he was thrilled afterward.
"I'm super happy," Gustafsson said afterward. "I can't believe it. It's a dream come true."
The 24-year-old Gustafsson is now 12-1 in his MMA career, with 11 of those 12 wins coming by stoppage in the first or second round, and his only loss coming to a very tough opponent in Phil Davis. Gustafsson is a rising star in the UFC's light heavyweight division.