"too few" or "to few"

Mostly you have to use "too" if you want to say something like, for instance, is "too much" or "too small".

If you want to say something like "aborting because of to(o) few players" what is correct there? too or to few?
I was corrected on several ocsasions on using "too few players". Help?

Thanks in Advance,
Andy