Club legend Thierry Henry now plies his trade for the latter, which Walcott thinks will make it an extra special occasion.
Furthermore, the 22-year-old has intimated that the Frenchman may soon be joined in the Big Apple by fellow fans favourite Lehmann.
"It is going to be an interesting battle I think and obviously we get to see Thierry come back as well," he said.
"I've heard a rumour that Jens might have joined them - I don't know if that's true - but again that is going to be great.
"It will just be great to play at the Emirates in front of the fans and hopefully show them what we can do and that we're ready for it.
"We won't treat it as a friendly - we don't really treat any pre-season game as a friendly to be honest - we like to go out there and win.
"And if we can win the Emirates Cup that will be great and then hopefully we can move on and try and win the league because that is the main one."