Although any game time may be limited, the sight of the 34-year-old former All Black playing rugby league for the first time since the 2014 NRL season, is sure to swell the crowd at Castleford's Jungle ground.

It will be the Wolfpack's first match since their Championship grand final win over Featherstone in October which clinched promotion to Super League while Williams' last rugby was for New Zealand in their World Cup third-place play-off victory over Wales in Tokyo almost 11 weeks ago.

The former Sydney Roosters back-rower underwent a rigorous pre-season camp in Kingscliff, NSW, before linking up with his new team-mates at their Manchester training base a fortnight ago.

Wolfpack head coach Brian McDermott says he has been impressed with the player's fitness.

"He's come back in great shape," McDermott said. "The guy's a training freak."

Toronto centre Ricky Leutele said: "His presence alone has changed the feeling around the club."

McDermott has also included his other close-season signings, Brad Singleton and James Cunningham, in his squad, with centre Chase Stanley the solitary notable absentee for the club's only pre-season trial match.

Castleford fans will also get a first glimpse of their club's new arrivals Sosaia Feki and George Griffin while half-backs Jake Trueman and Danny Richardson will play together for the first time.

Australian Associated Press