The match, which will take place at Ballymena kick-off's at 6.45pm, is sure to attract a big crowd and Gallick wants his players to give it their all.
"Obviously it goes without saying that this is the biggest game in the club's history, because to get into Qualifying One would a tremendous achievement for the club," said Gallick.
"It's a winner takes all game and it's a match which I'm hoping my players will relish."
The former City of Derry man is also praying his side can get that little bit of luck every side needs if they want to secure success.
"We need to play well on the day but we also need lady luck to be on our side, sometimes these big games are decided by the bounce of the ball and we hope that break of the ball falls our way.
"We have beaten them once at their place this season, while CYIMS have beaten us at Drumahoe, so we know it's going to be another tough match, but I have a fully fit squad to choose from and I expect all the players to be up for the game."
Gallick knows that there will be a big travelling support from the Waterside, however he's calling on all rugby followers throughout the North West to make the trip to Ballymena tomorrow evening.
"I know we'll have a lot of support from the Drumahoe area, but I'm hoping we'll get a big support from throughout the city and beyond," concluded the YM coach.