US captain Kathy Rinaldi has had a winning formula since taking over the Fed Cup team, and she's not expected to change anything in this year's final against the Czech Republic.

Under her charge since 2017, the US has won five straight matches, including last year's final against Belarus.

"Being a captain for last year and this year, every match you go into it you never underestimate any team," Rinaldi said Wednesday ahead of the weekend final on an indoor hard court at the O2 Arena in Prague.

"These are the two teams with most history in Fed Cup, the best record, so it's very exciting. We're honoured and humble to be here. For me as a captain to be in the second final is absolutely incredible."

However, after four of the top five US women in the WTA singles rankings - the Williams sisters, Sloane Stephens and Madison Keys - decided to skip the final, three players on the team have yet to play a Fed Cup match.

The 18-time champions have Danielle Collins as the highest-ranked player at No.36, along with 52nd-ranked Sofia Kenin and 63rd-ranked Alison Riske. Nicole Melichar is ranked 15th in doubles.

The Czechs have more reasons to worry about their sixth final in eight years.

After No.8 Karolina Pliskova was ruled out of the final with calf muscle and wrist injuries on Saturday, Czech Republic captain Petr Pala had some more bad news to announce on Wednesday about Petra Kvitova.

"Petra had a fever," Pala said.

"After an agreement with the doctors we decided she wouldn't be training (today)."

However, Pala added: "Nothing suggests she wouldn't be available for the weekend."

Missing Kvitova would be a blow for the Czech hopes. She contributed to all five previous titles, reaching fourth place among players with the most Fed Cup trophies.