"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 and Barbara Dickson. 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.

Göran Bror Benny Andersson is a Swedish musician, composer and producer best known as a member of the pop group ABBA and co-composer of the musicals Chess, Kristina från Duvemåla, and Mamma Mia! For the 2008 film version of Mamma Mia! and its 2018 sequel, Mamma Mia! Here We Go Again, he worked also as an executive producer. Since 2001, he has been active with his own band Benny Anderssons orkester.