Spoke to Luis last night. He said that he and his wife came up with the idea of the letter, after he said he was feeling upset that he hadn't been able to thank the fans or say goodbye. She then helped him decide what to put.
He's really excited about being back at Anfield (he'd been training there just before) and can't wait to walk down the tunnel (and touch the Anfield sign "with two hands") and run out onto the pitch. He said that, ever since the draw was made, he's been really dreading getting injured and not being able to play, but to date is fine. He reckons he'll start on the bench but really hopes he can play a bit, even if it's only for a few minutes. You could tell from his voice and face, he was genuinely excited about being back. Hope he gets the chance!
He's looking forward to hearing his song again too, so come on people, let's make it a good one for him.