For the win over Mexico, Ferdinand was certain King had done enough to convince Fabio Capello his body can stand up to the rigours of a four-week tournament.
Ferdinand said: "Ledley's a good player and good players play well alongside other good players.
"I enjoyed it. We both enjoyed it. He got a goal as well, which was great.
"From set-pieces everyone knows we are fairly decent and in the tournament hopefully that bodes well for us.
"Ledley had a great chance to show the manager what he can do and I thought he did a great job.
"Mexico qualified for the World Cup and they are a good team. We knew we were in for a tough game but by the end of it we were the team that controlled it."