Alexandre Lacazette and Laurent Koscielny scored to give Arsenal a massive London derby win over Chelsea to close the top-four gap to three points. Craig Burley breaks down how Unai Emery adjusted his Arsenal side to nullify Maurizio Sarri's rigid tactics for Chelsea. Alexandre Lacazette and Laurent Koscielny scored to give Arsenal a massive London derby win over Chelsea to close the top-four gap to three points.