England have been boosted by the news captain Lewis Moody's knee injury is not as bad as first feared.
The Rugby Football Union confirmed Moody suffered a mild ligament strain in his right knee in the 23-19 World Cup warm-up win against Wales.
He had a scan on Monday and the RFU is "optimistic" over his progress but no date has been set for his return.
The World Cup squad will be announced on 22 August with the tournament starting 9 September.
England play Wales in Cardiff on Saturday before their final warm-up match against Ireland in Dublin on 27 August.
Their opening match of the World Cup is against Argentina on 10 September.
"Is it realistic he will be on the plane [to the World Cup]? It is too early to say with that injury," said England's scrum coach Graham Rowntree.
"It is a mild strain, not a bad strain, which gives us hope. We will see how he develops over the next few days. He hurt his knee in January. On Saturday night he was optimistic he would get better. We have to see how he will go with the medics. We will take it week by week.
"We don't have to do any more than that."
Moody will not feature against Wales on Saturday, nor will prop Andrew Sheridan who continues his recovery from a shoulder operation.
Rowntree confirmed there was no definitive selection policy on whether England will travel to New Zealand with players carrying injuries.
But Moody's leadership is a key factor in the England squad.
"We will give him the time he needs," said Rowntree. "He is vital for us going forward. He has led from the front, led with energy and the guys respect him for that. He is doing a great job."
Moody, who was playing his first game for England since November after missing the side's victorious Six Nations campaign with knee ligament damage, was replaced by Northampton's Tom Wood midway through the second half.