Saints have been the competition?s outstanding team this season and coach Daniel Anderson has been impressed with the performances of his double-chasing players and he believes they will raise their game ahead of the Powergen Challenge Cup final.
Anderson said: "We are in a good frame of mind and there is a hunger from the players.
"We?re not sure what the team for the final will be but it?s not an issue at the moment.
"The players will not have to do much to their games in the next couple of weeks because I?ve got a lot of players who are playing well.
"It?s not like they?re playing badly and need to come good. There?s not much more they can do to showcase their form.
"If we stay as we are now players are going to miss out that are in good form."
Castleford, who are not yet clear of relegation danger but could still harbour play-off ambitions, will need to get last week?s disappointing 18-0 loss to Wakefield Trinity Wildcats out of their systems.
Anderson added: "I?m sure they?ll come out and be a bit annoyed at themselves for their performance but that doesn?t faze us.
"We expect a tough, torrid encounter anyway because they are a pretty bruising sort of team. That?s fine by us."
Saints will give a fitness test to scrum-half Sean Long, who was missing from the crushing win over Huddersfield Giants last weekend with an ankle injury.
Castleford Tigers 20-man squad: Platt, Shenton, Handforth, Kain, Sculthorpe, Henderson, Nutley, Bird, Huby, R. Fletcher, Viane, Fa?aoso, Manu, McGoldrick, Boyle, Edwards, Knowles, Ward, A. Fletcher, Payne.
St Helens 20-man squad: Wellens, Gardner, Lyon, Talau, Meli, Pryce, Long, Fozzard, Cunningham, Cayless, Gilmour, Wilkin, Sculthorpe, Roby, Hooper, P Anderson, V Anderson, Graham, Hardman, Fa?asavalu.
Referee: K Kirkpatrick