The Catalan opening looks as if it should be relatively harmless, combining as it does the Queen’s Gambit with the modest fianchetto development of White’s king’s bishop. But various endgame virtuosi, notably Petrosian, Korchnoi and Kramnik, have demonstrated that the Catalan can be dangerous. In particular, the nagging pressure exerted at first by White’s light-squared bishop may persist long into the middlegame and endgame.