Flanagan pokes the ball under Adrian, the fact that Adrian gets a touch is irrelevant really, he doesn't control the ball... which squirms under his hand, the same hand catches Flanagan's foot. Then Adrian's other hand wraps around Flanagan's ankle to make sure he brings him down. Even if the touch on the ball puts some doubt on the decision, the second grabbing on the ankle is stonewall, regardless of the fact he's just tripped Flanagan whilst getting a touch, the ball is still in play and Flanagan gets the ball back under control. Adrian is attempting to hamper this by grabbing the ankle. Flanagan plays on after that clip and gets the ball to Sturridge.