Novelty number two for Asian Cup 2019

Not long ago the Asian football confederation introduced video assistant referee system for the first time at its continental championship which is beginning early next year. Unfortunately, this technology will not be able to be seen in all duels, but nevertheless this news is a step forward to future tournaments.
And seven days ago the region has announced a new rule, but this time it is concerning to the game itself. Starting from game 37 up until 51 (or short: from last 16 and onwards) teams can make a fourth substitution. However, in the previous sentence there is a catch: this rule can be applied only if matches are going into...extra time.
To continue furthermore, this new regulation is also going to be used at the championships in youth categories of 19 and 23 years of age throughout the continent...