The 22-year old attacking midfielder badly rolled his ankle in the weekend's final regular season win over Gold Coast United and earlier this week was in major doubt to take on second-placed Central Coast Mariners in the first leg of their two-legged semi-final at Bluetongue Stadium.
But Nichols, who has scored six goals this season, is recovering well and will be given every chance of getting up for the clash says coach Ange Postecoglou.
"He's a lot better than what we thought," Postecoglou said.
"He had a scan and the scan was clear, that was good news ... so probably 50-50.
"We are giving him every chance to be right. I've got a sneaking suspicion it will be close."
And the Roar coach is not too worried about the fact his side have an away game to kick off their finals campaign.
"We haven't struggled in any of our games away from home which suggests our approach will work," he added.
"Our approach tends to be a fairly attacking one, so if we can go down there and get some goals it will put pressure on the Central Coast.
"If we score goals it's been proven that, more often than not, we will be successful."