Kenin also pushed Czech veteran Barbora Strycova, playing in her final tie for the Czechs after a 16-year Fed Cup career, to three sets on Saturday.
Barbora Strycova defeated Sofia Kenin 6-7 (5-7) 6-1 6-4 before Katerina Siniakova was more comfortable in a 6-3 7-6 (7-2) win over Alison Riske to put the hosts in a commanding position as they seek to win the tournament for a sixth time 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 previous year.
Riske, the only player on the United States team with Fed Cup experience, said all the pressure was on the hosts.
· The semi-finals: Czech Republic beat Germany 4-1 to reach the final, the us beat France, 3-2. U.S. captain captain Kathy Rinaldi gave credit to the Czech players but said, "I really think we could have been up 2-0, too".
World number seven Petra Kvitova of the Czech Republic has been ruled out of the opening singles of the Fed Cup final against the United States due to illness on Friday.
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.More news: 2018 midterm elections: Major ballot measures that passed
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"I'm really excited to go to the court".
Siniakova broke Riske for 6-5 in the second set but the 63rd -ranked American forced a tiebreaker.
For this final, three US players will make their Fed Cup debuts.
The 32-year-old Strycova, who has announced retirement from the Fed Cup after the final, struggled with her serve throughout a nervous first set. I fought for every ball, and I'm so happy I could win today in front of this crowd.
"I definitely do like the court a lot", she told media just after the draw was made.
"It is amusing because it is her first (Fed Cup tie) and it is my last one", Strycova said.
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.