Highlight Top n percent of range ignore duplicates

[ckaut2000]

I want to find a formula or conditional formatting that would automatically highlight the highest 20% of the scores in a row, but only the first 20%, no duplicates.
So in this case there are 13 values in each row, so 20% is 2.6 or rounding up, 3. So I want to highlight the 3 highest values, which should be the 8,8, and 9 in row 1
highlight1.xlsx

[martindwilson]

you say no duplicates but first row has 8 twice while second row only has one 4 and the rest ignored
=PERCENTILE(A1:M1,0.8) would give 8
=PERCENTILE(A2:M2,0.8) would give 4 so you could cf on the basis of >= percentile