Rio Paralympic champion Gordon Reid and silver medallist Alfie Hewett both made it into to the men's singles semi-finals on a rain-affected day in Tokyo.
With the pair on opposite sides of the draw, Great Britain are guaranteed at least a bronze medal in the event.
But quad doubles pair Andy Lapthorne and Antony Cotterill's bronze-medal match was suspended.
They trailed Japan's Mitsuteru Moroishi and Koji Sugeno 2-1 in the first set when rain fell.
The match was due to resume under the roof on the centre court at Ariake Tennis Park late on Thursday.
And the women's doubles semi-final featuring Jordanne Whiley and Lucy Shuker against China's Zhu Zhenzhen and Wang Ziying has been postponed until Thursday.
Reid, the fifth seed, got the better of fourth seed Gustavo Fernandez of Argentina but was made fight all the way before winning 7-5 3-6 6-1.
The Scot had won the previous five meetings between the pair this year, had trailed 4-0 early on but got into his stride and finished the set strongly.
Fernandez controlled the second set, breaking at key times to level the match, but Reid dominated the decider to set up a last four-meeting with Japanese world number one Shingo Kunieda.
It has been a challenging Games for the 29-year-old who had a scare after a member of the GB tennis squad tested positive for coronavirus just a day before the opening ceremony.
He was eventually cleared to play but had to follow a strict routine, which included only leaving his room for matches and practice and not socialising with team-mates.
"This morning was the first time that I could get out and go to the food hall myself and not have it delivered to the room because it's 10 days since the test," he said.
Hewett, who will team up alongside Reid in Friday's men's doubles final, booked his last-four singles spot by beating Frenchman Nicolas Peifer 6-3 6-4.
The Norfolk player will next face Dutchman Tom Egberink, who beat Spain's Daniel Caverzaschi.
"It was a tough match," said Hewett. "His level was quite high and fluctuated a little bit in each set so it made it very difficult to get a rhythm, but I can be contented with where I'm at."