Liverpool skipper Steven Gerrard is a major doubt for England's World Cup inaugural match against Paraguay on Saturday after declaring that he is not fully fit yet. Gerrard has been suffering from a back problem and has only participated in England's training on Thursday after missing the Wednesday session. “The back has been a bit of a problem over the last couple of days, I also got a knock on my hip and it just made my back go into spasm a bit,” Gerrard was quoted as saying by BBC on Thursday. England manager Sven-Goran Eriksson will be anxiously waiting on Gerrard's fitness status, but the 26-year-old midfielder didn't completely rule out his chances of catching the game. “Overall I have a good chance of playing, I've just got to keep working on it,” Gerrard said. “As we speak now it's probably 50-50, but if it keeps improving the way it has done over the past 24 hours I'll be there,” Gerrard added. Tottenham's Michael Carrick and Liverpool defender Jamie Carragher are the candidates to replace Gerrard if he isn't fit for the Paraguay game, with Carragher being the more likely candidate given his high defensive abilities.