Consider chordal SLE(8/3) in the unit disk from x to 1. For 0 < r < 1 let p(x, r) denote the probability that the SLE avoids the centered disk of radius r. We will derive a partial differential equation characterizing the function p(x, r). We will also discuss a generalization of this characterization to multiply connected domains and a definition of SLE(8/3) in such domains for which the resulting measure satisfies the restriction property.