The British United Cup team suffered a blow when their No. 1 player, Emma Raducanu, was forced to pull out of her match against Japan's Naomi Osaka on Sunday, but they rallied to win the tie in a decisive mixed doubles rubber. Raducanu withdrew hours before she was due to face four-time Grand Slam champion Osaka, citing an unknown injury.

She was replaced by world No. 276 Katie Swan, who suffered a 7-6(4) 6-1 defeat. But Billy Harris got the job done in the men's singles match, and Olivia Nicholls and Neal Skupski teamed up to win the tie for Team GB in a tight mixed doubles clash.

The Brits had already taken a hit when ATP No. 10 Jack Draper withdrew from the mixed-gender team competition last week. In his place, world No. 128 Billy Harris stepped up to play the men's singles matches for his country, and he beat Japan's Shintaro Mochizuki 7-6(4) 6-3 to start proceedings on Monday.

Raducanu was then expected to face Osaka, whom she has a 1-0 unbeaten record against. But the world No. 29 was unable to take to the court, and Swan took her place, losing in straight sets. It meant the tie went down to the mixed doubles, where Nicholls and Skupski beat Nao Hibino and Yasutaka Uchiyama 7-5 4-6 [10-7].

Japan had already lost to Greece on Friday, and the Japanese team has now been eliminated in the group stage. Team GB will face Greece on Monday in a winner-take-all tie, and captain Tim Henman is still hopeful that Raducanu will be able to take to the court.

Earlier in the day, he told Australian broadcaster Nine: "I got to be honest, she was very, very close. It was not an easy decision. She had been building up and practising really well. I don't think she is necessarily out of this tournament just yet."

Raducanu could play a crucial role if Team GB is to beat Greece and advance to the quarter-finals. The former US Open champion will face Maria Sakkari on Monday if she is fit enough to compete, and Raducanu has a 4-0 record against Sakkari.

For now, the Brits are savouring their win over the Japanese squad. After their decisive mixed doubles victory, Nicholls said: "Unbelievable, we had amazing support from the crowd. I've actually got family here who I'm staying with in Perth this week, which is making it even more special. We've had amazing team spirit this week. I've really enjoyed being part of this team. Just incredible to get the win."

Skupski added: "It's a great win for Team GB. Obviously, Billy started it off with a great win in the morning, and then obviously Katie had an amazing match against Osaka, so it was great for Team GB to come through, and then we've got another tough match tomorrow."

Henman is hoping Raducanu will be ready to play against Greece, but she's not the only one he's relying on. The British captain also called on any Brits in Perth to come out and support them. "We need them, we certainly need them. Greece have got a great team, and they started off strongly. We're going to enjoy this moment, and we're going to be ready to go tomorrow night," he smiled.