Aizen begins by slowly walking towards you. As he walks towards he removes his hands from his pockets, and lets the wind blow his robe away, revealing his sword that is on his side. He grabs onto his sword and takes a simple, single handed lower guar, the blade pointed down, and my feet would be shoulder width apart. I grip it firmly but not to limit the fluidity of my motions.
As soon as he fully unsheathes his sword he is within a 5m radius and quickly gets down on one knee and slams his left hand(free hand) on the ground, causing the ground within a 1m radius of you to drop down 2m.
(Doton: Chidōkaku) - Earth Release: Moving Earth Core
As soon as the ground drops, he pushes his left leg off the ground and heads towards you in the pit created at high speeds and creates a water rasengan in his fee hand.
He flies towards you and slams the rasengan into your head. The water rasengan, on contact, creates a dense torrent of water that throws you around like a child's play thing in the put.
(Oodama Rasengan) - Big Ball Spiral Sphere