It marked a winning return for the former Bayern keeper, as Inter defeated the German giants 2-1 in the first-leg of their Champions League quarterfinal.
"We had great energy inside us," Sommer told Inter TV.
"There were difficult moments during the match, but we remained compact and focused. We were very effective and the result is really positive for us.
"We were well positioned on the pitch. For me it was special to play here, in this stadium that I know well. We are happy with this victory."
Looking at the return-leg at San Siro, the Swiss added: "The second home game will be very important. The fans always give us a huge push, we will need their energy and our compactness to bring home the qualification. Then we will see."