Batum said it would be a "national disaster" if the hosts, considered the United States' bigger challengers, lost to France in Madrid.
The Portland Trail Blazers man said Spain had been preparing for a deep World Cup run for several years.
"As they [Spain] have said from the beginning - they are on a mission," Batum said.
"This is their World Cup. They play at home. They do not have the right to make mistakes.
"If they lose, I think it would be a national disaster. For them and for the whole country.
"Here they are ready. They have been building up to this for years so they know what they have to do."
Pau Gasol has led the way for Spain, scoring 20.5 points per game as his team cruised through six matches.
The teams met in Group A and Spain ran out convincing 88-64 winners and Batum said team defence would be the key for France.
"We have to stop them, defend in numbers," Batum said.
"We can't defend alone against [Pau] Gasol. It will be one against five. It'll be the same for [Juan Carlos] Navarro, it'll be the same for [Ricky] Rubio, for Marc Gasol and for [Rudy] Fernandez.
"You can name all the players, it will be like that for them all. To be successful you have to stay together as a team."
The winner of the clash will face Serbia or Brazil, who also meet in Madrid on Wednesday.
In their Group A clash, Brazil claimed an entertaining 81-73 win.
Leandrinho Barbosa (13 points per game) has led Brazil for points, while Miroslav Raduljica (14.5), Nemanja Bjelica (11.8) and Bogdan Bogdanovic (11.3) have impressed for Serbia.