"I Know Him So Well" is a duet from the concept album and subsequent musical Chess by Tim Rice, Benny Andersson and Björn Ulvaeus. It was originally sung by Elaine Paige (as Florence) and Barbara Dickson (as Svetlana). In this duet, two women – Svetlana, the Russian chess champion's estranged wife, and Florence, his mistress – express their bittersweet feelings for him and at seeing their relationships fall apart.