The 32-year-old, who scored a last-minute equaliser for Wolverhampton Wanderers against Liverpool in 2004, believes the Championship side can beat their Premier League opposition, but he warned the Bluebirds that they must be clinical.
“We have to impose ourselves on the game and put our good players in positions where they can create goals,” Miller told Wales Online.
“We’ve got Peter Whittingham, who is as good as anybody and could easily be playing in the Premier League right now.
“We are always capable of creating chances, either for me or for somebody else.
“But on days when you’re the underdogs, playing against a so-called better team, it’s important that you take those chances.”
Former Celtic and Rangers star Miller has played in three cup finals in Scotland – and the striker was on the winning side each time.
And while he admitted it was a special achievement for Cardiff to reach the final, he urged the Welsh outfit to complete the job by upsetting Liverpool on Sunday.
“It’s a cup final and it’s an occasion that you want to be playing in,” added Miller.
“It’s big for the club to be there, but we’re going fully focused on winning the cup.
“The build-up will be fantastic but when it comes to half past three and it’s time to kick off, all the lads will be fully focused on going out there and doing the job.
“Because we are a team from the league below, who really shouldn’t be getting to the final, it makes it all the more special an achievement for the club to get there in the first place.
“But now we’re there, we’re fully focussed on winning.”
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