Penkywicz, 26, scored a try in Thursday’s 39-26 at Featherstone to make it 13 consecutive wins for the Shaymen.
And he believes that ‘Fax should continue to play their way if they want to see off Super League Castleford.
“Maybe that’s where we’ve got the best chance of matching Castleford.
“But we’ll only know whether that’s true or not on Saturday night.
“They’re definitely red hot favourites, but it’s a one off game and you never know what is going to happen over 80 minutes.
“These are the games you want to play in though, playing against the best players in the best competition.
“Whatever happens, we will go out there and give it our hardest shot.”