Czech Davis Cup hopes hit by Hajek injury
A file picture of Czech Republic's Jan Hajek playing during the French Open in Paris, on May 29, 2013 - by Martin Bureau
The title-holders will reply on the trio of Lukas Rosol, Radek Stepanek and Jiri Vesely for the tie which starts on Friday.
"I decided against calling up another player given the complications of flying out to Tokyo and the training programmes of the players. But we have a team that is capable of winning out there," Navratil said.
Czech hopes of reaching the semi-finals for the third straight year as well as winning a third straight title have already been hit by the decision of top player Tomas Berdych to miss the tie.
Rosol, ranked 38th in the world and 49th-ranked Stepanek are likely to play in the singles and pair up again in the doubles with Vesely playing a backup role.
Japan, who have never won the Davis Cup, were given a scare on Friday when their top player Kei Nishikori withdrew from the semi-finals of the Miami Masters Series tournament with a groin injury.