The seasoned right-hander would replace all-rounder Scott Styris. McMillan had joined the squad before the first match after Jacob Oram was forced out of the game with a back strain.
Meanwhile, Australians Andy Bichel and Matthew Elliott have been added to the visiting squad for the second match.
The Black Caps won the opening game by a handsome margin of nine wickets on Saturday, raising more than 190,000 for the tsunami appeal fund.
New Zealand: S Fleming (Capt), N Astle, C Cairns, H Marshall, B McCullum (Wkt), K Mills, M Sinclair, C McMillan, D Tuffey, D Vettori, J Wilson.
Fica World XI (from): S Warne (Capt), A Bichel, M Elliott, I Harvey, G Hick, S Jayasuriya, L Klusener, N Knight, J Langer, M Muralitharan, J Rhodes, K Sangakkara (Wkt), H Streak, C Vaas.