By Ewan Murray Chelsea are aiming for back-to-back victories this Sunday when they host fellow London outfit West Ham United in the Premier League. The Blues picked up an important win against rivals Tottenham on Thursday evening, beating the Lilywhites 2-0 at Stamford Bridge. Another encouraging display against Aston Villa prior to that – a game in which they managed a 2-2 draw after falling two goals behind – means that confidence should be as high as it has been for some time. Meanwhile, confidence certainly won’t be flowing for West Ham at present, the Irons without a win in their last fiv…