"It is not going to be easy. After the 7-1 victory over Brazil everyone is thinking we are practically there," she told German broadcaster ZDF, referring to Germany's thrilling semi-final win over the tournament hosts.
"But a European country has never won a South American World Cup. That is why we all have to cross our fingers again, as Argentina will be trying very hard."
Asked to predict Sunday's score line Merkel said, "I don't mind, so long as we win."
Merkel attended Germany's first match in the Cup against Portugal and cheered the team on to a 4-0 win. Images of her at the game went viral online, including one of her posing with shirtless German players in the team dressing room afterwards.
Her vigorous celebrations of German goals - leaping to her feet and throwing her arms in the air - have sometimes irritated opposition fans, but have made her the darling of the German team, some of whom proudly tweeted their 'selfies' with Merkel.
Asked whether she was enjoying some free publicity by basking in the German team's success, Merkel replied, "I think people know in the end that I am the politician, and the footballers are the footballers." REUTERS