Quote Originally Posted by iCake View Post
чая is genetive, чай is accusative and also nominative, do not confuse the OP here. Выпить (что?) чай (accusative), выпить (чего?) чая. Чашка (чего?) чая. Подать (что?) чай. That's about it. Чаю is разделительный (partitive), which is now considered genetive.
Ok, my bad. Even the best of the best get overheated with such stuff.