Rooney was present at Ibrox in 2006 to watch the Hoops beat Rangers 1-0 thanks to a Maciej Zurawski strike.
The English superstar was there to watch former United team-mate Roy Keane in action for the Bhoys, but ended up the focus of the travelling fans' attentions. The familiar Rooney chants rang out and the powerful forward was hooked.
Watching him destroy Gordon Strachan's side at Old Trafford last week, though, it was hard to spot Roo's affection as he tore the Glasgow side to shreds.
Nevertheless, he told Celtic View about his adventures ahead of the Group E midweek return.
“That was a great day at Ibrox,” Rooney admitted, “But I'd been before, when I was about 16 or 17. Alan Stubbs had brought me up [from Merseyside] to see a European game at Celtic Park and I loved every minute of it. It was brilliant to go up and go into the players’ lounge.
“I’d always wanted to see a derby, though, so I went up two seasons ago - into the away end with all the Celtic supporters - and it was unbelievable.
“The fans were brilliant with me. As soon as I walked in, someone spotted me and I was handed loads of scarves and Celtic hats. It was all good fun and it was great to see Celtic win.”
However, he'll be cutting the Bhoys no slack on Wednesday, as he wants the Red Devils to secure safe passage to the last 16 with two games to spare.
“It would be nice if Celtic could finish second,” he added, “but that doesn’t come into my thoughts tonight.
“I’ll be going all out to get three points, as we want to secure our place in the last 16 as soon as possible.”
Liam Black, Goal.com