The two sides face off at The Oval this evening with the Glens yet to record a victory over the Invermen this term with three defeats and two draws in their two meeting to date.
With a money-spinning place in the qualifying round of the Europa Conference League up for grabs for the winner McDermott knows the importance of a win tonight, but admitted it won’t be easy.
“I hope so (get the win) but unfortunately it doesn’t work like that,” he told the club’s Youtube channel.
“Every time you play it’s a new game and a new challenge.
“It’s a quick turnaround, we’ve a couple of days to prepare.
“I’m glad we’re at home. Hopefully we’ll have a big crowd here and we’ll give it everything, but so will Larne.
“You prepare all season to try and win a trophy if you can, if you can’t win a trophy the minimum is to try and qualify for Europe.
“That’s Larne’s target and that’s our target too but unfortunately only one of us will have that after Friday night.”
The Glens saw off Glenavon in Tuesday night’s semi-final with Jay Donnelly and Conor McMenamin finding the net, but McDermott had special praise for midfielder Seanan Clucas.
“Seanan has been brilliant since he came here,” he said.
“He went through a rough time when he first arrived as he picked up a couple of red cards.
“He got a bit of stick for it but he’s a big strong character and he came through it.
“I think he’s earned the respect of the fans and definitely his team-mates and the coaching staff.
“Every time he’s out there you can’t not fault his enthusiasm, effort or desire to win and that’s what you need.”