The 27-year-old played against Fiji, Ireland, Italy – at Leeds United’s Elland Road – and France in the recent tournament but is now embedded at the South Yorkshire club and preparing to make his mark.
Gilmour must start on the bench as head coach Mark Jones, understandably, makes just one change to the starting line-up – centre Lloyd Hayes in for the injured Jordan Davies – after his squad’s last game, an impressive win over relegated Premiership club London Welsh.
Rotherham are fifth but only lead sixth-placed Nottingham by virtue of a superior points difference with both sides having started the campaign in promising form.
Nottingham have, too, defeated Welsh as well as winning on the road at Jersey and London Scottish of late.
“Nottingham have been very good this year and they’ve played quite well all season really,” said Jones.
“They just fell the wrong side of some results at the beginning of the season.
“They have a very good balance to their game; their kicking game, running game and maul game is very effective.
“It makes it very difficult to analyse them in what they are going to do and they’ll be a big test for us on Sunday.”
Indeed, the Championship as a whole is proving an intriguing competition so far, with Rotherham’s Broad Acres rivals Yorkshire Carnegie and Doncaster Knights both challenging hard and above them in the league table.
With the relegated side – Welsh – unusually struggling for form having lost four games already, and other teams clearly increasing their intensity in 2015-16, it is making for a fascinating campaign.
Rotherham, for their part, have secured five wins from their opening eight fixtures.
With all Championship clubs having had last weekend off due to the World Cup Final, the Titans will now look to make that six victories before a fortnight of British & Irish Cup action gets underway with Leinster’s visit next Saturday.
If they are to be serious contenders for a play-offs place for a third successive season, Rotherham know tomorrow’s game is just the sort of fixture in which they must prosper.
That is looking ahead, though, and Jones – impressing in his first campaign – is concentrating on Nottingham.
“We’ll have to approach the game with the right mentality and get our own house in order,” said the former Wales winger.
“It’s an away game and you have to go there with the fundamentals in place; the set-piece has to be strong, you have to get your kicking game right when you’re in your own third and when you have the ball you have to make sure you maintain it.
“After that you can start looking at how to attack the opposition, but first and foremost you have to get the fundamentals right.”