Following his £15m summer move from Swansea City, James has been one of the stars of United's difficult start to 2019-20.
At 21, James will be one of the younger players in Wales' starting XI in Slovakia, yet he feels at home in the red jersey.
"I think I've grown into the Welsh team really well since that game against Slovakia," he says.
"A year ago I wasn't really playing for Swansea, but everything just happened so quickly. It is just a case of how you grasp that.
"If you'd said to me a year ago that I would now be playing regularly for Manchester United and Wales I'd have said: 'Don't be silly'.
"But things happen so quickly in football and you have to be ready for anything.
"It is a very proud moment for me to be playing for my country every time I'm picked. There is going to be pressure this week, but I'm used to that now."