Leinster's fringe Ireland contingent get the chance in Cardiff tonight to remind Andy Farrell they are available if needed over the course of the Six Nations.
The province face Cardiff Blues at the Arms Park (7.35pm), with academy lock Joe McCarthy making his debut alongside Devin Toner, who at the opposite side of the scale makes his record-extending 272nd appearance.
Among those starting or on the bench are skipper Luke McGrath, Ciarán Frawley, Will Connors, the Byrne brothers Ross and Harry, Rhys Ruddock and Ross Molony who missed out on Ireland selection.
"Andy Farrell's message would be the same as mine really, you just need to play rugby and put your hand up," said Lancaster.
"Will Connors is a good example. He's played 20 minutes of rugby (versus Ulster in November) in I don't know how many months.
"He's obviously disappointed not to be involved (with Ireland), his last game might have been Scotland, bar that 20 minutes he played.
"So he wasn't expecting to get picked. Harry's not been playing, he's had one or two little injuries - so they all know that the best place for them is to be playing rugby and be playing for Leinster.
"There's nothing worse than sitting around thinking and having nowhere to put your frustration.
"Luke McGrath would be in that situation. Rhys Ruddock, Ross Molony, the list goes on of lads who are probably just on the fringes.
"Our message to them is, 'let's get into preparing for Cardiff'."
Lancaster is a big fan of Crawley, the Skerries-born 23-year-old who can play at out-half, centre or full-back. He will be partnered by Naas' Jamie Osborne tonight, who makes his 11th appearance for the province.
"I think he's very versatile, number one," said the former England head coach of Frawley.
"We're obviously blessed at Leinster with three very good out-halves, so to be able to play him at 12 is a real bonus, because he's got that physical and athletic presence that you need in a 12 as well. And as you saw at the weekend, the ability to bring him on at 15 as well.
"So to have that armoury where he can play 10, 12 and 15 is excellent. But I think it has been good for him just to nail his colours to one mast, to put himself in the ball-playing 12, but also the ability to carry and do everything else.
"I think he's come on in leaps and bounds recently. It will be great this week, because there's a good chance he's going to start at 12.
"Obviously he's disappointed, as all the lads are who were just on the fringes of missing out on the Ireland squad, but we've got Cardiff on Saturday, you've got Frawls, you've got Jamie Osborne.
"So we've still got the ability to put out a really good backline and have a look at someone like Jamie, which will allow Frawls another chance to show more leadership in a team that has less experience, because we've got 16/17 Ireland boys having left.
"I think he's in a really good place. I know the Ireland coaching team think a lot of him. It's just for him to get more experience now in this window.
"Ironically the cancellations during Christmas have benefitted this pool of players, because we'll now play more in the Six Nations window than we were originally set to do.
"We'll play five, six games before the Six Nations finishes, so that's going to be key. And as you know, all it takes is one injury, and suddenly he could be called up anyway."
Leinster: Jimmy O'Brien, Adam Byrne, Jamie Osborne, Ciarán Frawley, Rory O'Loughlin, Ross Byrne, Luke McGrath; Ed Byrne, Seán Cronin, Michael Ala'alatoa, Devin Toner, Joe McCarthy, Rhys Ruddock, Will Connors, Scott Penny.
Replacements: James Tracy, Peter Dooley, Vakh Abdaladze, Ross Molony, Max Deegan, Nick McCarthy, Harry Byrne, Tommy O'Brien.
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