Petain is near Farrer Road Mrt.
Bus service - 857, 64, 65, 66, 67, 147 etc will take u there. Bus stop to align near Exit G of Farrer Road Mrt. Map as below :
http://www.streetdirectory.com/asia_...evel=6?187,290
Exit at "H" on Farrer Road Mrt & follow the map direction to reach the "red star".