The Premier League side face Bradford City of League Two, with the Yorkshire club having knocked out Wigan, Arsenal and Aston Villa on the way to Wembley.
The Welsh side, in their second year in English football's top flight, belied their own underdog status to knock out Liverpool and Chelsea in their cup run.
But despite the 71 places separating the two clubs in the league, Rangel is wary of the favourites tag that Swansea have for the final.
"It's a bit unusual," the 30-year-old admitted to AS. "For the first time we are not the underdogs, but we have beaten Liverpool and Chelsea. Of course, anything can happen in a final."
Swansea's run to Wembley and their current eighth place in the Premier League has seen manager Michael Laudrup linked with Real Madrid and Manchester City, and Rangel can understand why the Dane is so highly-rated.
"Yes, I think he has many requirements to be a big manager. He has been a player himself, understands the game, knows how he wants his teams to play and has the respect of the players."