Chelsea are threatening to derail one of West Ham United’s most exciting summer transfer window plans. The summer transfer window will be a vitally important one for West Ham manager Julen Lopetegui, and the same can be said for new Chelsea boss Enzo Maresca. Lopetegui certainly has more work on his hands at the London Stadium than Maresca does at Stamford Bridge though. There is set to be a big player exodus from the London Stadium before the start of next season, so Lopetegui will have to make a whole host of new signings. The 57-year-old apparently has six new signings planned for the Hamme…