South Africa's fifth-most capped player and second-highest point-scorer, with 50 caps and 261 points to his credit, arrived at Newport today after signing a two and a-half year deal for a reputed Â£300,000.
And he has been immediately put in the Black and Ambers squad for their Welsh Premiership game against Swansea on Saturday.
Coach Leigh Jones has no concerns about including the talented fullback.
'Percy played his last game in the Currie Cup two weeks ago and is in excellent playing condition,' Jones said.
'However, we will see how he shapes in a training run on Friday before making any decision on whether or not to play him.'
Welsh international Jason-Jones Hughes is set to end his injury exile by playing for the Newport Under-21s against Swansea at Rodney Parade on Saturday. If he comes through that game, he will be joined by Ian Gough, Jonathan Pritchard and Andy Powell in the Newport United fixture away against Bristol Shoguns United on Monday, 11 November.
Backs: Matt Pini, Percy Montgomery, Matt Mostyn. Alex Cadwallader, Scott Williams, Luke Nabaro, Hal Luscombe, Shane Howarth, Jason Strange, Ofisa Tonu'u, Llyr Lane, Dale Burn.
Forwards: Rod Snow, James Richards, Paul Young, Adrian Garvey, Chris Anthony, David Pattison, Simon Raiwalui (captain), Mike Voyle, Matthew Veater, Joe Powell, Jason Forster, Gareth Gravell, Steve Ojomoh, Rhys Jones.
Newport and Ebbw Vales start well