Glory found itself overtaken by previous cellar dweller Wellington Phoenix after falling to a 1-0 defeat in Auckland on Saturday.
But given the compressed nature of the bottom half of the ladder and with eight rounds still to go, Ferguson is confident there is all to play for.
"If you win four or five of these games, you will reach the finals," he said.
"Everybody has got to play each other and get points off each other, so there's still the belief we can do it."
Perth has picked up just two points from its past seven games and has not won since Christmas.
But Ferguson said there was enough quality in his squad to make the play-offs.
The problem was getting his top side on the park, with the likes of skipper Jacob Burns, Shane Smeltz, Michael Thwaite and Liam Miller out at different stages.
"We've definitely got the quality; we've definitely got the squad," he said.
"It's just trying to get them all playing at the same time."
Both Burns (back) and Smeltz (groin) sat out the match at Eden Park and Ferguson was hopeful that Smeltz, at least, could back to bolster the attack for the trip to Melbourne Heart next weekend.
"He's trained the last couple of days and he's been training at good intensity, so when we go back we'll have a bit more news on him," he said.
"But I don't want to rush him. At the end of the day, he's had this injury for quite a while now.
"We have to make sure that, when he comes back, he's going to be 100 per cent fit and hopefully scoring goals for us."
Ferguson described Burns as being more of doubt to face Heart at this stage.