James made a successful return from long-term hamstring injury to help Chelsea win at Nottingham Forest.
Asked if the fullback can make the Euros, Pochettino said: "Massive. It's unlucky there are only two games ahead and it's one week. It is important for him to recover for his feelings and he is such an important player for us. He is our captain. We all love him. Yes, important, and to see whether he will be fit and have a chance of making the Euros.
"We have one more week to work. He is doing well in the training sessions.
"After four or five months, he's not the same to train and compete but if he has the possibility to do that in the next two games, and if his coach in the national team believes he can cope with the competition, I think he will be ready."