Tactic Toolbox Open Sicilian3. d4 is the most popular response to the Sicilian, both at grandmaster and club level. The theory of the opening is huge and grows continually. Knowing typical tactical patterns is important to keep the upper hand in these sharp lines. Roeland Pruijssers and Nico Zwirs show patterns you should know when playing the Open Sicilian. The interactive Fritz Trainer format invites the viewer to answer questions and helps to test and deepen your knowledge.