That's football for you. Always expect things like that once in a while. Although looking at various aspect to judge this match, Arsenal has all it takes for a successful win. My most surprise is how Newcastle could defeated them without a goal.
Newcastle have a really tough defense for Arsenal in the EFL Cup this season so in the first leg and also in the second leg of the EFL Cup competition Arsenal really couldn't score against Newcastle and that has indeed made some people very surprised at Arsenal's performance. But Newcastle also still can't be sure of winning the competition if Liverpool successfully make it to the final and face Newcastle to show who is the best in the EFL Cup competition this season.