The midfielder is on loan at Blackburn Rovers this season in the Championship.
He has made 11 appearances so far this season, and will now get a chance to impress on international duty.
Youngster Harvey Elliott, who is a part of Liverpool's first-team setup, will also be joining Morton with the Under-21s.
Elliott was expecting a senior call-up, but he will be with the Young Lions instead.
There are two Liverpool players with the Under-20s, four with the Under-19s, and two more with the Under-18s.