The Toon, led by a Faustino Asprilla hat-trick, edged Barcelona 3-2 at St James' Park in the 1997-98 Champions League group stage and although that was an enormous achievement, Hexham-born Forster believes Celtic's win at Parkhead late last year was a bigger triumph.
"Obviously I watched a lot of Newcastle when I was growing up and they were doing well in Europe at the time," he said.
"I remember watching on TV with my family when they beat Barcelona 3-2 at St James', which is probably the best of a lot of good memories of European football growing up.
"I was only nine or 10 at the time so at that age I was just enjoying playing football and would never have imagined that one day I would play against Barcelona and win.
"Of course it was a big win for Newcastle at the time but I don't think it compares to the result we had this season because the Barcelona team back then wasn't as good as they are now.
"The current side is widely considered the best team in the world and everything about that night at Celtic Park was special."