Garde's men lie third in Ligue 1, which would give them a passage into the qualifying competition. However, failure to beat Rennes at the Stade de Gerland might allow fourth-placed St Etienne, who have a superior goal difference, to squeeze past them.
Lille, in fifth, could also overhaul them if they lose on the final day.
Garde, whose side is already assured a place in the Europa League, told olweb.fr: "There is maybe a risk of playing in fear, but I will do everything in my team talk to make sure that it does not happen.
"At a very high level, there is always pressure and nerves. But once the game starts, that stress disappears.
"The group has worked well throughout the week. It's a very, very important game."
Lyon head into the final day in good form having lost only one of their last six games, with that defeat coming against champions Paris St Germain.
Midfielder Steed Malbranque has recovered from a knock and will feature, but defender Samuel Umtiti is struggling with a thigh injury and midfielder Maxime Gonalons is suspended.
Rennes' ambitions are more modest heading into the final 90 minutes of the campaign, although victory could see them climb into the top 10.
However, the omens are not particularly good with Frederic Antonetti's men having lost seven of their last nine league games and won just one, claiming only four points from a possible 21 in the process.
The match is Antonetti's last before he stands down as Rennes coach after four years.
Current Real Sociedad boss Philippe Montanier will be in charge at Stade de la Route de Lorient next season.