Sri Lanka won the toss and opted to field first in their Champions Trophy Group B match against New Zealand at the Wanderers on Sunday.Sri Lanka made the surprise change of replacing veteran off spinner Muttiah Muralitharan with seamer Thilan Thushara, while New Zealand have brought in fast bowler James Franklin for batsman Gareth Hopkins.Defeat for New Zealand would rule them out of semi-final contention completely while a loss for Sri Lanka would leave them reling on other results going their way to advance.TeamsNew Zealand: Jesse Ryder, Brendon McCullum (wk), Martin Guptill, Ross Taylor, Grant Elliott, Neil Broom, James Franklin, Daniel Vettori (capt), Kyle Mills, Daryl Tuffey, Shane Bond.Sri Lanka: Sanath Jayasuriya, Tillakaratne Dilshan, Kumar Sangakkara (capt/wk), Mahela Jayawardene, Thilan Samaraweera, Thilina Kandamby, Angelo Mathews, Nuwan Kulasekara, Thilan Thushara, Lasith Malinga, Ajantha Mendis.