Buttner, who stepped in for the rested Patrice Evra, admits it was a dream to make his United bow and says he felt even better to contribute in his first outing.
"When I stood on the pitch on Saturday, I thought 'how have I ended up here'," he said.
"It has all happened a bit fast. You hope to get some minutes on the pitch, but I was suddenly in the team.
"I heard about it first on Friday from Rene Meulensteen (United coach) and then from Ferguson.
"I'm just going to enjoy playing football and I really enjoyed my debut I'm learning here every day."