The Basel defender played in his side's 3-0 win over Honduras on Wednesday, which assured Ottmar Hitzfeld's team a berth in the last 16, but they face one of the pre-tournament favourites in Argentina, who have won all three of their games in Brazil thus far.
However, Schar says that while Switzerland are relieved to be progressing after their thumping defeat at the hands of France, both he and his teammates go into this game with nothing to lose.
Schar told reporters: "We have reached our main goal and we can now play without pressure.
"We are clearly the underdogs against Argentina and we want to use the opportunity."
The last time the Swiss reached the last 16 of a World Cup, in 2006, they were beaten by Ukraine after a penalty shootout.