King capped a fine season with Tottenham by making his first international appearance for three years in Monday’s friendly defeat of Mexico.
The 29-year-old is now widely tipped to be part of Fabio Capello’s final 23-man squad, and the centre-back is confident his body will not let him down.
“With the knee I’m confident,” said King, who scored England’s opener in a 3-1 win.
“I played three games in the last week of the season so it proves I can do it and can play games in quick succession. And the Wembley pitch was quite energy sapping. The more I play the fitter I get, and the medical staff are doing a brilliant job to help me prepare for the games.”