Katie Boulter beat fellow Briton Alice Gillan 6-1 6-4 on the opening day of the Progress Tour Women's Championships but Katie Swan withdrew injured.
Boulter, 23, who has dropped to 374th in the world after injury, will play another two matches in the round-robin stage at Roehampton's National Tennis Centre.
"It was tough conditions but I found a way to win," she told BBC Sport.
Earlier, Swan retired from her match against Alicia Barnett.
The British number six, who had won the first set, was visibly upset when she was forced off the court with a right hip injury with the score at 6-4 1-4 and then later pulled out of the event.
At 254 in the world, Swan was the highest ranked of the players in the tournament after Heather Watson and Harriet Dart withdrew with ankle and groin injuries respectively. However, Boulter has a protected ranking of 85 following her injury lay-off, and can use it to enter tour events and is the favourite to win this domestic tournament.
The event - in which players call their own lines and collect balls under coronavirus restrictions - consists of two four-player pools before a semi-final knock-out stage.
Aside from the Premier singles that features Boulter, there is also a doubles competition and a Division 1 singles event.
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