Okuri-ashi-barai
(advanced foot sweep)
"Break Uke's balance to his right and sweep his right
foot towards his left with your left foot. 
For
the technique to work you must stay loose and move smoothly.
Put the sole of your foot as close as possible to Uke's outer
ankle and sweep just as he is shifting his weight to his left
foot. Be sure to sweep with your whole leg, not just your
foot. Sweep in the direction his foot is traveling."
