How to calculate Tajima's D and Fay & Wu's H for unphased data?

[RoseString]

Hi,

I have a small number of samples (~10) for my species of interest (non-model organism), so it's almost impossible to phase the data. I am interested in doing some site-frequency spectrum methods to detect positive selection in the genome, but they require the calculation of nucleotide diversity (pi). Is it possible to do so without phasing the data?

Thanks in advance!

[GenoMax]

For reference cross-posted: https://www.biostars.org/p/179347/