Robertson was mindful of McGrath's ability to recruit players, including former English import Saul Halpin who has switched allegiances from the Blues for Miramar Rangers this winter.
"Saul's been successful for us and he has gone on to the national league and achieved top honours there with scoring goals so they brought him out years ago and we're expecting a tough game from them [Taranaki] certainly."
Taranaki, who are comeback kids after bowing out in 2010, have three wins and Rovers one.
Robertson says Rovers' preparation was good considering they have footed it quite well in the league but haven't come away with the results.
"You know, we've had some really good games and then some sloppy periods which have cost us, so it was good to have a decent performance last week and get a win under our belt for confidence [4-2 at Marist Palmerston North].
"The lads have trained well this week, so they are prepared to claim three points on the road."
English midfielder Fahad Rwakarambwe has been dropped to the reserves for game time, while centre back Danny Wilson will not travel to away fixtures for the rest of the season due to family commitments.
TEAM TARANAKI: 1 Santiago Fernandez (GK), 3 Jeremy Hill, 4 Paul Cunningham, 5 Joel Willets, 6 Jack Roberts, 7 Jeremy Hawkes, 8 Russel Laird, 9 Ben Moore, 10 Wade Randle, 11 Tyler Stephens, 12 Rodrigo Mangini, 13 Nathan Hill, 14 Sandro Grandi, 15 Phillip Shehan, 16 Dom Squatriti, 17 Sam De St Croix, 18 Vance Hoskin, 19 Brad Hickling, 20 Joshua Smith, 21 Damien Mosquera, 22 Sam Adeyinka, 23 Mustafa Can, 24 Nicolas Varela, Nick Hayward (RGK).
Coach: Ian McGrath.
NAPIER CITY ROVERS: Ruben Parker Hanks (GK), 2 Blake Koolen, 5 Matt Bruin, 6 Oliver Coren, 7 Jean-Michel Paulin, 8 Chris McIvor, 9 Angus Kilkolly, 11 Jorge Akers, 12 Ethan Ladd, 14 Josh Stevenson (vc), 15 James Hoyle, 17 Fergus Neil (c), 18 Ross Willox, 19 Bill Robertson, 20 Charlie Yexley, Kyle Baxter (RGK).
Coach: Bill Robertson.