Coach Sven-Goran Eriksson warned England they would be beaten by World Cup favourites Argentina on Friday if they repeated their poor second half performance in the 1-1 draw against Sweden.
"Hopefully, we will be play better football and not just for 45 minutes. We need to play for 90 minutes to get a good result against Argentina," he told reporters on Thursday.
"It's a very difficult game, an important game and we have to get a result if we want to play in the World Cup after the 12th of June," Eriksson said after a training session.
"We know it's difficult, they're one of the best teams in the world. But hopefully it's not going to be easy for them."
Argentina, who beat Nigeria 1-0 in their opening group F game, can guarantee themselves a place in the second round by beating their arch rivals. England play Nigeria on June 12.
Eriksson is expecting more from his captain, David Beckham, who lasted only 63 minutes against the Swedes in his first game for seven weeks since breaking a bone in his foot.
"He will be even better tomorrow and hopefully can play 90 minutes - and do it even better than he did the first half against Sweden," said Eriksson.
Beckham warned on Wednesday that Argentina might resort to the kind of provocation which led to his own red card in St Etienne four years ago, but Eriksson has no such fears.
"I'm sure they are as focused as we are on having a good game and getting a good result, so I'm not afraid of that," said the former Lazio boss.
"I had many of those players at Lazio. I know them and they are professional footballers, as we are."
More than any provocation, Eriksson sees the main danger from Argentina being the strength of the squad, and in particular, striker Gabriel Batistuta who scored the winner against Nigeria.
"I've always said they are one of the favourites and they played very well in their first game," he said.
"They had many chances and could have scored more goals. If you see the whole Argentina squad, they are all top-class, world class players."
Comparing them with the Swedes, he added: "You're going to meet even more individual skills tomorrow. They are extremely quick and technically very good.
"And up front they have an extremely strong player who seems to be in very good shape at the moment."