Poor tackling allowed England winger Ben Cohen to go over for a soft try for Saints after just two minutes and that score ultimately proved crucial.
But new Scotland skipper Gordon reckons this young Glasgow team, who take on Toulouse in France on Friday night, still have a chance of progressing.
Gordon argued: "The try that we lost early on just goes to show that you pay dearly for just one mistake at the highest level in Europe. "A couple of new boys have come in this season - Kevin Tkachuk at prop and Dan Turner at second row - and we are starting to gel.
"In addition, Dan Parks, Sam Pinder, Sean Lamont and Graeme Morrison were all making their Heineken Cup debuts. It is a step up and they will know what to expect next time.
"We aren't scared of Toulouse. The way we have been playing for the last few weeks will give us confidence. We can take the game to anybody on our day."