Painted Discs

A box holds 3 flat discs, each with two faces and each face painted a single colour: one disc is green on both faces, one is yellow on both faces, and one is green on one face and yellow on the other. You shake the box, pull out one disc at random, and drop it on the table without looking at the underside. The face pointing up is green.

What is the probability that the hidden face (the one against the table) is also green? Give the answer as an exact fraction or a decimal.