Eighteen-year-old Amir, who finished with figures of 6-84 and the man of the match award in England's innings victory, said he did not know why he had cleared the poppingcrease with his front foot.
Following the decision to refer Michael Beer's "dismissal" of Cook that proved to be a no-ball and denied the spinner a maiden Test wicket, Johnson revealed that the front line of the poppingcrease is not of paramount concern during practice.