Last updated on .From the section Tennis
A struggling Emma Raducanu lost the opener on day two of Britain's Billie Jean King Cup qualification in the Czech Republic, meaning that she must win her match to keep the tie alive.
In cold conditions on the outdoor clay, Marketa Vondrousova defeated Raducanu 6-1.
The second singles match is between Dart and Linda Fruhvirtova.
The best-of-five tie goes to a doubles decider if Dart wins.
The Czechs have won the tournament six times in a row, and they lead 2-1 after both teams won on Friday.
The runners-up will face a play-off tie the same week as the winners.
Britain is one of the countries bidding to host the finals.
The US Open champion was hoping to give Britain the lead in the tie for the first time by beating Martincova on Friday.
In 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.
The one-sided first set lasted 26 minutes and was dominated by her opponent.
The British player had to leave the court for treatment before the start of the second set because of blisters on her foot.
Vondrousova, ranked 32nd in the world, moved 2-0 ahead, but then seemed confused by the lack of movement and lost concentration.
The Czechs won the next four games to seal the victory in 62 minutes.
More to come.