Serbian defender Milan Bisevac scored his maiden goal for Lyon, heading home Clement Grenier's free-kick in the 64th minute, to give the Ligue 1 club a one-goal lead over Grasshopper in their two-legged UEFA Champions League qualifying tie.
With a spot in the Champions League play-off round on the line, Garde was thrilled to have kept Grasshopper scoreless, but maintained the job is not over for Lyon.
"This is a good result as long as we qualify but we are only halfway through this important and difficult tie," Garde said on Tuesday.
"The fact we did not concede a goal tonight in a home tie could prove vital.
"The match was very tight and tough but this was not a surprise for us."
Lyon had nine shots to seven from Grasshopper at the Stade de Gerland with the hosts hitting the target five times, while the Swiss visitors failed to test the French side's goalkeeper Anthony Lopes.
"Zurich are a very well organised team and will work hard throughout the game," Garde said.
"They are very good defensively and they don't have many flaws to expose.
"We found it very difficult to score or develop good chances in the final third but I repeat - not having conceded a goal is important and we did not look like conceding either which is a credit to the performance of our defenders.
"They did have two good free-kicks where we were perhaps lucky not to lose a goal.
"However, at the end I'm pretty happy with my team's effort and the result."
Despite holding out Grasshopper in France, Garde is convinced the Swiss club will score on their home turf next week.
"I believe that Zurich will score, therefore we must take every opportunity to try to score an away goal that will count double for us," the 47-year-old coach said.
"Both teams are of a similar level and both work hard.
"For us, it was our first official game, Grasshopper has already played three.
"That proved important this evening because they looked sharper than us."
