Petra Kvitova has been ruled out of the opening day of the Fed Cup final because of illness.

The clash between the Czech Republic and defending champions the United States at Prague's O2 Arena takes place this weekend, with the home side appearing overwhelming favourites when the teams were announced.

The US side is missing four of its five highest-ranked players in Serena and Venus Williams, Sloane Stephens and Madison Keys, with teenager Sofia Kenin, Alison Riske and Danielle Collins the singles picks alongside doubles specialist Nicole Melichar.

But after Karolina Pliskova pulled out of the Czech side through injury earlier this week, the hosts suffered another blow with Kvitova also sidelined, at least for Saturday's singles rubbers.

The clash will begin with Kenin taking on Barbora Strycova before Riske faces Katerina Siniakova.

The reverse singles, for which Kvitova could be drafted in if well enough, take place on Sunday, ahead of the final doubles rubber between world number one pair Siniakova and Barbora Krejcikova and Melichar and Collins.

The Czech Republic have won 10 straight ties at home and, as the dominant force in the competition over the past decade, are looking for a sixth title in eight years.

The USA can take comfort in their record against their opponents, having not lost to the Czechs in eight meetings dating back to 1985, while they are on a seven-match winning streak after beating Belarus in the final last year.

US captain Kathy Rinaldi said on "We came here expecting their best players to play, so we were preparing for everyone.

"I believe in all my players. We'll see what happens - we're prepared, we're ready to go."