Loew confirmed Wagner, who earned his first cap this week in a friendly draw in Denmark, would be their starting striker in Nuremberg as they prepare for the Confederations Cup starting in Russia later this month.
"Tomorrow, Sandro Wagner will be playing from the start," Loew told reporters. Wagner received the call-up after netting 11 times for Hoffenheim this season.
Loew said Julian Draxler, who is nursing a minor injury, was racing to get fit in time and would remain captain if he played.
"With all due respect to San Marino, tomorrow it is all about how we will approach the game and not how San Marino will play."
Germany, missing half a dozen key players after Loew chose to give them a longer summer break ahead of next year's World Cup, will still want to come close to the 13-0 result against San Marino in 2006.
"It is not really realistic with this new team to go on a new record hunt," Loew said. "Clearly we want to win, we want to show fans enjoyable fun football and also score a lot of goals."
The Germans, reigning world champions, are competing in the Confederations Cup in Russia starting later this month, with their first Group B match against Australia in Sochi on June 19.
The Germans are also top of their World Cup qualifying group on a maximum 15 points from five matches, five clear of second-placed Northern Ireland. The Czech Republic are third on eight points.
(Reporting by Karolos Grohmann; editing by Mark Heinrich)
