It's not a tackle, it's an interception to win the ball which is travelling across the pitch
Check up on what defines a tackle in football.
Once you understand it is not a tackle, it then switches to interpreting Johnson's play in that context. Obvious risk of injury is not a consideration.
Serious foul play has to have physical contact, in order to be regarded as serious foul play.
A mere millimeter out from physical contact, it becomes a question of dangerous play. In this incident, Johnson clearly gets to the ball first, cleanly with his outstretched foot.
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