The Renfrewshire club go into the home game with Sheffield Steelers having lost eight of their last nine games, leaving them clinging on to the final play-off spot.
And with third-top Sheffield providing this evening's opposition, Gardner knows Clan must produce the goods on home ice to stand them in good stead for the return next Tuesday.
He said: "I've never been to Sheffield, but I believe getting ahead in the first leg will be so important.
"We've got to win the game, or at least draw. I would hate to go down there with them having a lead.
"We're not favourites so we need a big effort. Everyone has to be on top form."