Emma Raducanu is the highest-ranked player in the British team, which also features Harriet Dart, Katie Swan, Sonay Kartal and is led by captain Anne KeothavongGreat Britain's bid to reach the Billie Jean King Cup play-offs started with defeat for Harriet Dart against the Czech Republic's Marketa Vondrousova.
Dart, 25, has been in decent form this year, but found it difficult on clay against the 2019 French Open runner-up.
Vondrousova, who is the home team's highest-ranked player in the Prague tie, won 6-1 6-0.
Emma Raducanu takes on world number 50 Tereza Martincova in Friday's second singles rubber.
US Open champion Raducanu will play her first senior match on clay, as well as making her debut in the Billie Jean King Cup.
The best-of-five tie features two singles matches on Friday, followed by two on Saturday and one doubles rubber if needed.
The winners will qualify for November's finals, while the runners-up face a play-off tie the same week.
Britain are among the countries bidding to host the finals and could also still qualify as the host nation.
'She didn't let me play well'
Raducanu, 19, leads a new-look British side in Prague, with the side not able to call on either recently retired Johanna Konta or Heather Watson for the first time since 2010.
Captain Anne Keothavong recognises it is a "changing of the guard" and says she is excited by the crop of young players she has at her disposal.
But they face an uphill task against the Czechs, who have won the team event six times since 2011, on the outdoor clay, even though they are without star trio Barbora Krejcikova, Karolina Pliskova and Petra Kvitova.
Dart broke into the world top 100 recently after reaching the fourth round at Indian Wells, but she was unable to deliver a strong start for Britain.
Vondrousova is ranked 32nd in the world and her quality on clay showed.
British number two Dart broke serve in the opening game but was unable to maintain the pressure - particularly struggling on her own serve and producing seven double faults - as she lost in just 55 minutes.
"It was a very challenging match. I just feel like I need some more time on the clay. I'm very inexperienced on the surface and she is a Grand Slam finalist on this surface," said Dart.
"She definitely put me under pressure a lot. I didn't feel my best but she also didn't let me play well."
