To remove such stain I would recommend that you sponge the area of your shirt with a weak vinegar solution and then wash it according to the fabric instructions. For that I would recommend a mild detergent with oxy contents (many are avialble in the market).
The only thing I've had any luck with is, if the stain is on a white part of the shirt, you may be able to get it off with clorox cleanup or some similar product. If the collar or sleeves are white you have to insure that you don't get it on any other part of the shirt. When you first spray it on, it will sometimes turn to a bright yellow. Leave it for a short while and then rinse the whole shirt in case it has bled somewhere else.
Put shout on it, it works - trust me.
I swear by wd-40....give it a try...seriously it will work great especially on polyester. Good luck!