ONE PIECE Episode 161: The Ordeal of Spheres! Desperate Struggle in the Lost Forest!
Episode 161 of 1180 of ONE PIECE, aired July 20, 2003, 25 minutes. Available with English subtitles and dub where released.
Episode summary
Usopp, Sanji and Luffy fight Satori, but the power of Mantra seems to be too strong.