Redknapp is now back in for him with QPR chief executive Phil Beard and chairman Tony Fernandes trying to push the deal through.
Redknapp said: "I have been over to Porto and met him, it's a difficult deal to do.
"I met the boy and had a good chat and it was great. It's up to the chairman in the end, it's finances and it is down to the chairman and Chief Executive, not a lot down to managers.
"It's out of my hands now really. Good player if we could get him. I think it's a difficult one."