The support team, alpha team in this case, should not immediately fire on the enemy upon sight. You can try and get your assault team into as good of a position before initiating contact. Ideally you want that L shape before you initiate fire, that way you have lots and lots of interesecting fields of fire. Another thing to note is the mad minute, and the fact that you dont have the three to one ratio, so security during this process would be needed to make sure that your own attack doesnt get attack itself, then your engaged on two sides, a poor situation. Speed is the key in this type of 1:1 ratio scenario, as well as obtaining total supression, mainly through fire superiority, over your target. If you are well versed enough you can skip shifting fire and instead move the fire down the line as your team assaults through, that way if there is anyone left in there you dont lose that suppressive ability over them, but you want alot of practice before doing that.