The 27-year-old made the crucial stops in his side's penalty-shootout win over the Netherlands to set up the showdown with Die Mannschaft in Rio de Janeiro later today.
Romero has insisted that they are a stronger team than the side that was defeated 4-0 by Joachim Low's men in the quarter-finals of the 2010 tournament.
He told reporters: "We can beat Germany. I am relaxed. That 4-0 defeat against Germany was a hard blow, especially after a World Cup in which we played well.
"But, on that day, nothing came off for us. The post, the chances but, well, four years have passed and we hope to do things better than we did that day.
"The thing about this squad and this team, no matter who we play or who plays for us, is that we are united. We are strong, determined and together. That's why we believe we can beat Germany. We'll do it for our country."
Argentina can win their third World Cup if they defeat Germany later today.