Teenager Jack Draper gained a shock win over Cameron Norrie on the second day of the Battle of the Brits in Roehampton.
Draper, 18, ranked 303rd in the world, triumphed 7-6 (7-5) 7-6 (7-4) against world number 71 Norrie at the National Tennis Centre.
British number one Dan Evans bounced back from Sunday's loss to Andy Murray by beating Jan Choinski 7-5 6-0.
Heather Watson eased past Jodie Burrage 6-1 6-4 in the women's competition.
Elsewhere, Emma Raducanu defeated Katy Dunne 6-1 6-4, Beth Grey won 6-2 6-2 against Naomi Broady, and Eden Silva beat Alicia Barnett 6-2 2-6 10-7.
In the other matches in the men's event, Liam Broady recovered from a set down to overcome James Ward 3-6 7-6 (7-0) 10-8, while Aidan McHugh overcame Anton Matusevich 6-4 2-6 10-8.
The event has been organised by the Lawn Tennis Association to help British players prepare for the 2021 season with competitive matches after their schedules had been affected by the coronavirus pandemic.
No ball girls or ball boys are being used at the event, although there are umpires and officials.
Court One: Eden Silva v Naomi Broady, Jack Draper v Jay Clarke, James Ward v Jan Choinski, Alicia Barnett v Katy Dunne.
Court Three: Jodie Burrage v Francesca Jones, Dan Evans v Liam Broady, Andy Murray v Cameron Norrie, Heather Watson v Emma Raducanu.
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