In most of China, espresso drinks are more common than drip coffees, so that can cause confusion. When I lived in Xi'an, I would ask for
黑美式咖啡,不用加牛奶。
美式咖啡=Americano
I successfully got black coffee that way. There might be a shorter way to say it, though--I'd love it if natives could teach me a better way to order it.