It is thought that the club from Anfield send scouts out to Spain to watch the 24-year-old in the Scottish Champions agonising 2-1 defeat to Barcelona.
The Reds are of course desperate to add to their strike force in the New Year as they are short of options right now and have a whole host of injury problems.
Hopper has proven in recent years that he is a natural goal scorer and he is likely to relish a move to the English Premier League.
Some suggest that the Scottish Premier League is not a good indicator of whether a player is good enough for a club such as Liverpool, but any striker that is putting the ball in the net on a regular basis deserves a chance.
Also, the Essex-born man has proven in the Champions League what a good player he is.
However, Celtic are set to fight tooth and nail for their most prized assets and it could take a big bid from Brendan Rodgers to secure his services in the January transfer window.
We shall see.