With doubts over David James' fitness and Joe Hart's lack of experience Green could face his Hammers colleague when their two countries meet in their opening Group C match in Rustenburg on 12 June.
And Spector would not be surprised to see the 30-year-old between the posts for that fixture and the whole tournament.
"I always personally felt confident having him behind me, that if something goes wrong, he'll be there," said the American.
"I think he's the most consistent as well, compared to the other England keepers. That's something Fabio Capello or any manager would value in a World Cup, especially when there's a lot more pressure, the kind of pressure the England team will be facing going into it."
The Manchester United forward and player of the year has been in impressive form this season and the USA international admits keeping him quiet will be tough.
"Rooney was in unbelievable form before his injury. It didn't seem like you could stop him or take him out of the game," Spector told whufc.com.
"I think we need to limit his contribution as much as possible. He has so many great attributes and scored many goals and scored so many headers, which we haven't seen in the past.
"It's not a job of one person to defend against him, but the team in general. He's very clever. Sometimes he drops off in the midfield to find space and pick up the ball and run at you.
"It's pretty well-known England are going to be more direct and I think we'll need to defend well as a group in that respect."