Here is the databook entry for it:
Exclusive to Sasuke, proud recipient of the Uchiha blood, this ultra-fast combo attack requires an advanced physical condition and a certain knack for it. The opponent is tossed into the air and shadowed with Shadow of the Dancing Leaf. Upon inflicting a blow, one takes advantage of said opponent's counterattack to spin around and rise again for further assaults. Since the fall is increased in velocity with each blow, the damage when one is eventually struck to the ground is unconceivable.
The first blow is parried. But the lion bares his fangs, one after another…!
The strength from the assaults generate a high-speed fall, that strikes together with the final blow!!
The only requirement for Sasuke's combo move is an advanced physical condition. No mention of needing to open the Eight Gates.
And this is what the databook says for the move that Lee does prior to the Front Lotus:
A jutsu where one follows the opponent, closely matching their body's movement, just like a leaf that dances in the air is followed by its shadow. This move by itself is harmless, but it is usable as a stepping stone for a great many powerful jutsu like Front Lotus and so forth. That said, it also has a rather high degree of difficulty, and by the looks of things, those among the genin-class who can manage a flawless use of this high-grade taijutsu would be the likes of Lee, Sasuke or Neji.
At that point, Lee physically restrains the opponent by binding them and switch to Front Lotus!
So from the looks of it, the actual Front Lotus technique is the spinning piledriver as I thought.
