The Dragons have peaked at just the right time, defeating both Leeds and Huddersfield in closely fought play-off encounters so far.
Meanwhile Saints, who finished top of the table after 27 rounds, comfortably saw off Castleford in their opening play-off game, giving them a week off last weekend.
Prop Alex Walmsley does return though, following suspension.
Catalan coach Laurent Frayssinous names an unchanged squad, although does have injury doubts over a handful of players.
St Helens 19-man squad: Makinson, Turner, Jones, Swift, Hohaia, Masoe, Roby, McCarthy-Scarsbrook, Soliola, Manu, Laffranchi, Flanagan, Amor, Wellens, Walmsley, Percival, Wheeler, Richards, Thompson.
Catalan 19-man squad: Escare, Pomeroy, Oldfield, Bosc, Elima, Henderson, Lima, Taia, Anderson, Mounis, Maria, Pelissier, Whitehead, Millard, Bousquet, Baitieri, Duport, Garcia, Williams
LRL Prediction: Might be a game too far for the Dragons – Saints to book a place in their first Grand Final since 2011.
Last ten meetings:
Super League summary
St Helens won 11
Catalan Dragons won 8
St Helens highest score: 53-10 (H, 2007) (also widest margin)
Catalan Dragons highest score: 42-0 (H, 2014) (also widest margin)