While it's not exactly ideal preparation for a decider, Williams says "it's the best of the situation we're in" as Raiders feeder club Mounties vie for the reserve grade premiership against Illawarra at Parramatta Stadium.

Williams went from Canberra to Sydney on Thursday afternoon to train with Mounties before flying to Melbourne to be on standby for the Raiders in their preliminary final should disaster strike.

Then the NSW Cup player of the year will jump on a plane back to Sydney on the morning of grand final day.

Williams could find himself training in front of over 30,000 fans before being whisked away to play in front of not many – it's almost like groundhog day.

It was the same story last week as Williams warmed up with the Raiders in their sudden-death semi-final against the Penrith Panthers before being bundled into a car to play a preliminary final in Sydney.

In "a pretty whirlwind 24 hours" Williams had gone from 21,000 screaming Raiders fans to the pouring rain at Leichhardt Oval, and he didn't even get to watch the NRL game.

"You come to get a little bit used to it," Williams said.

"Obviously you'd love to be playing in front of those big crowds but we're a pretty close group of mates up at Mounties and the coaching staff do a lot of good things for us, so it's just about going there and trying to perform well and do your best."

The Raiders haven't won a reserve grade title since 2003 – coincidentally, the last time the NRL side finished in the top four before this year.

Williams grew up a Raiders fan and remembers that game clearly as a Raiders side featuring the likes of Terry Campese, Michael Monaghan and Phil Graham trounced St. Mary's 31-6.

Now he will look to win the club's second reserve grade title against the man he partnered in Canberra's 2012 NRL finals charge – Illawarra hooker Josh McCrone.

"Josh is one of the most competitive people I've ever played with," Williams said.

"He puts his heart and soul into the game and he's a very skilful player as well. We'll have to watch Joshy, he's probably a pretty big key to their success down there.

"We need to make sure we nullify what he brings to the table so I'm sure he'll be up for a big game as well playing against his old club but hopefully we can get one up over him."

Mounties will be bolstered by a number of players with top grade experience in Shaun Fensom, Adam Clydsdale, Brenko Lee, Zac Santo and Glen Buttriss among others.

The winner of the NSW Cup grand final moves into the State Championship match on NRL grand final day against the winner of the Queensland Cup grand final between the Redcliffe Dolphins and Burleigh Bears.

NSW CUP

Grand Final: Sunday - Mounties v Illawarra Cutters at Parramatta Stadium, 4:15pm. TV Time: Live on Fox Sports 1.