Ahead of today's trip to West Ham, Hiddink said: "Everyone knows we don't have a natural replacement for the left-back position so we have to improvise.
"So Bosingwa will start there, although he doesn't know that yet.
"I decided Bosingwa would play the moment Ashley was booked in the quarter-final against Liverpool.
"You have to deliver an option.
"Whoever plays against Messi has a tremendously difficult job to do. Messi is one of the most productive players in the world when he's performing.
"But we've practised a few days with Bosingwa in the left-back spot."