A struggling Emma Raducanu lost the opener on day two of Britain's Billie Jean King Cup qualifier in the Czech Republic, meaning Harriet Dart must win her match to keep the tie alive.
Raducanu lost 6-1 6-1 to 2019 French Open finalist Marketa Vondrousova - and was hampered by blisters - in cold conditions on the Prague outdoor clay.
Dart, 25, plays Linda Fruhvirtova in the second singles match.
If Dart wins, the best-of-five tie goes to a doubles decider later on Saturday.
Vondrousova's win means the Czechs, who have won the tournament six times since 2011, lead 2-1 after both teams picked up one victory on Friday.
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.
US Open champion Raducanu, who beat Martincova on Friday to level at 1-1, was aiming to put Britain into the lead in the tie for the first time and give the momentum to a new-look side.
But, in what was only her second senior match on clay, world number 12 Raducanu came up against a wily opponent, who is a natural on the surface and has proved that with her results.
Raducanu, 19, was unable to cope with her opponent's variety and court-craft in a one-sided first set, which lasted just 26 minutes.
The Briton needed to go off court for treatment before the start of the second set, apparently for blisters on her foot, and struggled to move properly when the match resumed.
Vondrousova, ranked 32nd in the world, moved 2-0 ahead but then seemed unsettled by Raducanu's lack of movement and lost concentration.
Raducanu was gifted a break back, only for the Czech to refocus and win the next four games to seal victory in 62 minutes.
More to follow.
