The 22-year old landed awkwardly on his ankle in Saturday night's 4-0 demolition of Gold Coast United and admitted it was still fairly tender.
"I can't really put much pressure on it," Nichols said.
"You don't want to miss any game, but if I do have to miss this game hopefully I'll be fit for next week.
"We've got enough depth in the squad to cover."
The Roar meet the Mariners at Bluetongue Stadium this Saturday in the first of two legs at 7:00pm. The return leg will be at Brisbane's Suncorp Stadium next week.