Here is how WCRB summarizes the content on their BSO page:
In an encore broadcast, BSO Music Director Designate Andris Nelsons leads the orchestra in Wagner'sSiegfried Idyll and the Symphony No. 3 by Brahms, and Paul Lewis is the soloist in Mozart's Piano Concerto No. 25.(Some emphasis added.)
That page also contains a number of links you might wish to follow.
As usual, the concert broadcast, available also over the web by clicking the "Listen Live" button on the WCRB home page, begins at 8:00 p.m., Boston Time. Based on my review of 11 months ago, I think you'll enjoy it.