The Czechs have won the title in five of the last seven years, but in 2017, the U.S. beat them in the semi-finals on the way to the title.
Kvitova has been troubled by high temerature after competing at the WTA Finals in Singapore and did not train this week.
The teams may change after day one and if Kvitova gets better, she is certain to appear on the court on Sunday.
"I believe in all my players. I feel pretty at home", she added.
Kvitova returned to the team this year after recovering from injuries she suffered during a knife attack at her home in December 2016.
But, propelled by the sold-out O2 Arena, the four-time Fed Cup victor regained composure in the second to sweep aside the Russian-born Kenin, who is still in search of her maiden WTA singles title.
"Despite everything, we're still the favourites because our girls are great players", Czech captain Petr Pala told reporters.
They remain heavy favourites, even without their leading duo, against a United States team featuring three debutants, including Kenin. "I'm still very confident about my team".
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Both players made 32 unforced errors and the American had 23 winners _ two more than Strycova _ but the Czech made her experience count in the decisive points.
Strycova carried the momentum into the third and withstood a late challenge from the American for a resilient victory - the first time in her distinguished Fed Cup career that she had fought back from a set down to win a singles rubber.
Petra Kvitova has been ruled out of the opening day of the Fed Cup final because of illness.
"We can only be aggressive and go after it tomorrow", Riske said.
On Sunday, Siniakova is due to face Kenin and Strycova will then take on Riske.
Siniakova responded to the setback by easing to a 3-0 lead, while she came out on top in a dramatic fifth game - in part thanks to a fortunate net-cord - that spanned 19 minutes, making it 4-1.
"I'm really looking forward to it", Riske said.