Heather Watson gave Great Britain a 1-0 lead in their best-of-three Fed Cup match with Latvia in Estonia.
Watson, the world number 72, beat 307th-ranked Diana Marcinkevica 6-3 6-0 in 61 minutes in the day's first match.
World number 10 Johanna Konta plays 35th-ranked Jelena Ostapenko, before Jocelyn Rae and Laura Robson play Marcinkevia and Ostapenko.
Great Britain beat Portugal 3-0 on Wednesday, and face Turkey in their final group match on Friday.
Unlike the men's team competition, the Davis Cup, which has a World Group of 16 nations, the Fed Cup divides its top teams into two groups of eight - World Group I and World Group II.