Emma Raducanu withdrew from her tie against Naomi Osaka as Great Britain started their United Cup campaign against Japan in Australia.
The British number one has not played since October and no reason was given for her pulling out against Osaka in Perth, in the lead up to the Australian Open, which begins in Melbourne on 18 January.
“I have to be honest, she was very close,” GB team captain Tim Henman told Australian broadcaster Nine.
“It wasn’t an easy decision. She had been building up and practising really well. But we just felt this morning it was a little bit too early.”
Great Britain face Greece after their Group E tie against Japan.
Henman added: “I don’t think she’s necessarily out of this tournament just yet. So we’re keeping our fingers crossed.”
Raducanu has struggled for form and fitness since winning the US Open in 2021 but, last season, completed 50 matches for the first time in her career and is 29th in the women’s rankings.
The 23-year-old pulled out of two exhibition matches in the United States in December because of a minor foot issue before starting her preparations for the 2026 season with coach Francisco Roig in Barcelona.
Ties at the United Cup comprise of one men’s and one women’s singles match and a mixed doubles.
Billy Harris earned GB a 7-6 (7-4) 6-3 victory against Shintaro Mochizuki before Katie Swan, who replaced Raducanu, was beaten 7-6 (7-4) 6-1 by Osaka.
Neal Skupski and Olivia Nicholls are representing Britain in the mixed doubles against Yasutaka Uchiyama and Nao Hibino.
