Coach Mark Ring accepted a request from the Wales management team for Madden to join the squad for a one-off appearance as Llanelli do not have a game this weekend.
"We have had a lot of examples in Wales of clubs putting their own interests ahead of the national team, but that has been ridiculous.
"As a coach I am only to glad to help and I know the club is equally keen to back the national cause," Ring told the Western Mail.
If Madden comes through this game unscathed, it will raise speculation that he will be included in Steve Hansen's squad that face Ireland in the RBS Six Nations Round 4 match against Ireland in the Millennium stadium next weekend.
Madden has been absent for a month with a shoulder injury he sustained during Llanelli's 39-26 win over Cardiff in the Welsh Premiership.
But he is short of match practice, and will be primarily looking to get some match-time under his belt before being cast into the international cauldron.
"I want to get back to playing for Wales," said Madden.
"But I need to give my shoulder a test. And this weekend is the perfect time to do it."
Madden seems set to take the place of Caerphilly regular Darren Sweet.
Caerphilly: S Tuipulotu; O Ashman, R Boobyer, S Cox, G Lewis; L Richards, A Chiltern; L Manning, C Ferris (capt), M Madden, D Davies, P Jones, A Williams, J El-Abd, M Workman.
Replacments: J Murphy, J Thomas, D Sweet, F Vunipola, N Rouse, S Grainger, G Jones.
Neath (from): Backs: Gareth Morris, Allan Bateman, James Storey, Kevin James, Adrian Durston, Dave Tiueti, Shane Williams, Shaun Connor, Andy Moore (capt), Patrick Horgan. Forwards: AN Other (hooker), Adam Matthews, Paul James, Andrew Millward, Adam Jones, Andy Newman, Lyndon Bateman, Ben Davies, Alfie Mocelutu, Steve Tandy, Rowland Phillips, Jamie Ringer.