"We have already sold over two million shirts," Adidas boss Herbert Hainer told SID, an AFP subsidiary.

"I had to get a shirt for an acquaintance and it was pretty difficult, even for me.

"And from what I have heard, the stores are also pretty much sold out."

If Germany beat Argentina in Sunday's World Cup final at Rio de Janeiro's Maracana Stadium to win a fourth title, Adidas will start producing shirts with an extra fourth star over the German FA (DFB) badge.

"The shirts with the three stars on will probably soon become collectors items," said Hainer.

"They should all be snapped up quickly - just like the shirts with a fourth star on."

After Germany crushed Brazil 7-1 in Tuesday's semi-final wearing their black-and-red striped away shirt, the alternative shirt has also been snapped up by eager 'Mannschaft' fans.

"We were surprised by how well the away shirt has sold," admitted Hainer.