The in-form Borussia Monchengladbach striker will not travel with the team to Kiev because of a stomach virus and is the second forward to be ruled out with Miroslav Klose also missing the first of two friendlies this month.
"Some thoughts I have had now need to be changed because I had planned to have both Klose and Reus and maybe even starting with both of them in Ukraine," Low told reporters.
"These were my thoughts but I need to rethink this as they will hopefully join the team on Saturday," said Low after the unveiling of Germany's Euro 2012 strip, a v-neck white top with three thin diagonal stripes in the colours of the German flag.
Low had said he was interested in playing a 4-4-2 formation and trying out a two-pronged attack despite having chosen to field one forward for the past two years in his favoured 4-2-3-1 system.
The 51-year-old said he would still experiment in the friendlies despite the absences, which also include the injured Bastian Schweinsteiger.
"Our team is well-oiled, much better than two years ago. The philosophy has gone deeper," he said. "The foundation has been laid correctly and that allows me to vary our game a bit in those two matches."
He ruled out, however, using players who are active in European competitions with their clubs for the full 90 minutes over both matches.
"Players still competing in the Champions league will not play over 90 minutes twice. Maybe they come in later or even after half-time."
