Sydney are suffering a shortage of bodies with Patrick Wood testing positive for COVID-19 this week while Rhyan Grant, Joel King and Andrew Redmayne are away with the Socceroos.

First-team regulars Kosta Barbarouses, Adam Le Fondre, Luke Brattan, Michael Zullo and Calem Nieuwenhof are all out of the game at Leichhardt Oval with injuries.

But Montgomery, whose regular centre back Kye Rowles is away with the national team for this month's World Cup qualifiers, says the Sky Blues still hold the upper hand.

"We go with a squad of 18, I think they have a squad of 23," he said.

"If you do the maths on that we are missing one when they are missing three, they still have more players than us.

"I'm delighted for Kye. Hopefully he gets some minutes because it's a great experience for him.

"Sydney are a big team with a big squad and a big budget and we are a small group of players with some scholarship boys who make up the squad.

"The next few weeks are going to be testing for everyone's squads."

The Mariners, who lost 3-1 to Melbourne City last time out in the league, will welcome back Dan Hall, Lewis Miller, Josh Nisbet, Garang Kuol and Nicolai Muller after they were all ruled out with COVID-19.

Central Coast, who have already claimed wins over Sydney in the FFA Cup and A-League Men this season, will also have Jason Cummings on deck after his move from Dundee.

Montgomery said the Scottish striker had passed all the appropriate fitness tests after arriving in the country and would come into calculations for a debut.

"We got him ticked off and he's trained the last two days," Montgomery said on Saturday.

"You can see he is a quality player and his finishing is top class.

"You don't score that many goals in Scotland and in England unless you're a good finisher.

"He's definitely available and I'll be picking a team around the boys returning and I'll put a team out that I feel is going to win the game."

Australian Associated Press