( CNN ) -- Italy have admitted they do not know when star goalkeeper Gianluigi Buffon will be able to return to action at the 2010 World Cup . Buffon , who helped Italy win the tournament in Germany four years ago , had to be substituted at half-time during his team 's 1-1 draw with Paraguay on Monday because of a sciatic nerve problem . The Juventus stopper initially said he hoped `` to recover in two days '' but an official Italy team statement was less optimistic . `` [ He ] has a strong sciatic problem , '' it read . `` It 's impossible to estimate when he might return . '' Italy 's next match is against New Zealand on Sunday June 20 , with a contest against Slovakia four days later . The Azzurri had to come back from a goal behind against Paraguay and will need to improve dramatically if they are to win the tournament and match Brazil 's record haul of five World Cups . Meanwhile , Dutch winger Arjen Robben is still eight days away from full fitness , according to Netherlands coach Bert van Marwijk . Robben was back in training on Tuesday following the hamstring injury which ruled him out of their 2-0 victory over Denmark , but is likely to miss the June 19 clash with Japan . Spain midfielder Andres Iniesta is fit for Spain 's opening World Cup match against Switzerland on June 16 after overcoming a thigh injury . And England duo Ashley Cole and Wayne Rooney returned to full training on Tuesday having rested on Monday to recover from the 1-1 draw with the United States .
Italy midfielder Michael Buffon is out indefinitely with a back injury . Italy face New Zealand on June 20 after 1 - 1 draw with goal in opener . Dutch midfielder Arjen Robben is still eight days from full fitness , the coach says . Influential Spain midfielder Andres Iniesta fit to face Switzerland on June 22nd .