Alfie Hewett defeated countryman and doubles partner Gordon Reid in a dramatic battle to reach his second grand slam final at the US Open.
This was the first time Britain's two leading wheelchair players had met at a slam and it went down to the wire.
Hewett looked set for victory at a set and 5-3 but Reid hit back and led 5-3 in the deciding set only for Hewett to force a deciding tie-break.
That featured match points for both men but it was 19-year-old Hewett who hit the winning lob to claim a 7-5 5-7 7-6 (10/8) victory after three hours and two minutes.
He said: "I'm a bit speechless right now. It was an amazing match, he's a great sport and a great athlete.
"It was absolutely exhausting. I'm glad it was me."
The teenager won just three games when they faced each other in the Paralympic final in Rio last year but Hewett has made rapid strides while 25-year-old Reid has struggled to reproduce his 2016 form.
Hewett won his first grand slam title at the French Open in June and will now aim to double his tally when he takes on France's Stephane Houdet in the final on Sunday.
First Hewett will team up with Reid to take on Houdet and Nicolas Peifer in the doubles final.
Hewett and Reid joined forces to win their third grand slam doubles title together.
The pair defeated French top seeds Houdet and Peifer 7-5 6-4 to add to their Wimbledon titles the last two years.