Diabate pulled Griggs down off a scramble against the fence and immediately took his back, sinking his left hand under Griggs' neck in the process. He tightened it and got a near-instant tap at 2:05 of the first round.
"I was looking for the knockout but he gave me the opportunity so I went for it."
Diabate nearly finished Griggs even earlier, flooring him with a stinging straight left in the opening 30 seconds. Griggs was able to survive that moment but was never able to gain any momentum as Diabate took him down multiple times and beat him up with knees and elbows.
The 6-foot-6 Frenchman has now won three of his last four after gaining his first octagon submission win. He's 19-8-1.
Griggs, who was competing at light-heavyweight for the first time, fell to 11-3. It was his second straight loss since coming to the UFC from his previous home in Strikeforce.