The South Korean striker is set to line up for Bayer Leverkusen in tonight's Champions League clash.
"I was a United fan as child and I was always happy when they scored," he said. "Now I'm going to be playing at Old Trafford and that's a great honour. I'm really looking forward to it.
"I'll learn a lot in the match and it will be really special moment for me but I will try my best to win the game."
For the big stories and the banter follow us on Twitter: @tribalfootball