How do players link Alistar's Headbutt and Pulverize in an instant?

Watching the pro players, whenever someone plays Alistar they somehow chain pulverize and headbutt in an instant. Does anyone know how they're doing that?

This is something that can only be done with a very low ping and decent hardware.

Essentially you press W and target the enemy and then immediately press Q while you are traveling to complete the Headbutt. This will cause Alistar to execute his Pulverize as soon as his Headbutt animation has finished. Because the enemy has a travel time from the Headbutt, the Pulverize will interrupt their movement and instead knock them up into the air.

If you ever see an Alistar seemingly activate his Pulverize and pound the ground for no reason, it is most likely because they attempted to perform this combo but the target was out of range.

right as you headbutt you quickly pulverize and instead of getting to far away they go up into the air. Its like if malphite ults in a straight line and alistar is in that line not at the end of it and pulverizes right when malphite is on top of him he will interrupt malphite's ult and malphite will just end up being pulverized.

to instant headbutt>pulverize you headbutt your target and immediately after press pulverize. just remember that this creates a quick and unsuspected CC and is less efficient than headbutt + pulverize or headbutt into a wall > pulverize.

Instant headbutt > pulverize creates an opportunity for a quick gank if your jungler is very close, or creates a kill opportunity for your AD carry (assuming they have CC like vayne's condemn)

To add more information to the previous answers, you pulverize while you are in motion of headbutt. If you are smartcasting, you'll want to be careful to be in range of the headbutt, so you just don't pulverize the ground.

Do not try to do it with smart cast it is very important to know the exact range of your headbutt so that you can time it correctly. Nothing makes teammates more angry than someone knocking someone to safety that they were about to kill. Try the Smart cast range indicator in the more options in your main menu it should help you learn the range. Once an Alistar has practiced enough it becomes second nature.