Nelson started for England Under-19s in their 2-0 victory over Montenegro on Wednesday, as the Three Lions made the perfect start to the defence of their UEFA European Under-19 Championship title.
The Leicester City loanee played the full 90 minutes, with goals from Luke Chambers and Sonny Perkins earning England three points in a qualifying group also containing Georgia and Denmark.
Slicker was also named in the starting eleven for his country, as Scotland Under-21s beat Northern Ireland 3-1 in an international friendly.
The goalkeeper, on loan from Manchester City, also played the whole game, as goals from Kieron Dowie, Ben Doak and Josh Mulligan earned Scotland the win.
England now face Georgia on Saturday and Denmark on Tuesday, whilst Scotland take on Northern Ireland again on Sunday.
