The Crows fell agonisingly short against Melbourne on Sunday, left to rue woeful inaccuracy from set shots in the 14.13 (97) to 13.15 (93) loss at the MCG.
Adelaide's third straight defeat put them in danger of dropping out of the finals race - six points adrift of eighth-placed Geelong - ahead of a huge clash with cross-town rivals Port Adelaide.
"We're still fighting. We're still playing in relevant games and we're confident that we can still win every game we go into," Nicks said.
"We've got five to go and I think that gets us what we're after (if we win them all).
"That's a pretty big ask - we go into a Showdown next week against a top-two side - but that's what we're about."
Adelaide lost defender Nick Murray to a knee injury during the third quarter against Melbourne before Rankine went down clutching his left hamstring in the final few minutes.
The livewire forward had kicked three goals, taking his tally to 35 in 18 matches for the Crows this season after a high-profile switch from Gold Coast.
"Izak's no expert but he's had a hammy before and he's talking about it like it's similar," Nicks said.
"I think he missed a couple (of matches) last time, so fingers crossed that's not a major hammy or tendon.
"I'm no expert in that area but I'd say we'd probably lose him for a few weeks."
Prolific ball-winner Rory Laird could be back to face Port Adelaide, with Nicks to reassess his midfield mix after veteran Matt Crouch's impressive display against Melbourne.
Crouch had 22 disposals and a team-high seven clearances in his second senior appearance this season.
"He was probably held out slightly because of Rory Laird playing in our side - they're similar players - but we could look at that going forward," Nicks said.
"But I thought today he played a really important role."
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