Britain's Andy Lapthorne and Jamie Burdekin finished as runners-up in the quad event in the Wheelchair Tennis Doubles Masters in California.
The pair were beaten 6-4 4-6 6-3 by top seeds David Wagner and Nicholas Taylor of America.
GB star Jordanne Whiley and Japan's Yui Kamiji remained on track to retain their women's doubles title.
The Grand Slam-winners beat Germany's Sabine Ellerbrock and Britain's Lucy Shuker 7-6 (7-4) in the semi-final.
"I was struggling with my forehand to start with, but Yui got us through until I relaxed and found my confidence," said Whiley .
"It wasn't my best performance today, but we make a great team and after our amazing year at the Slams, hopefully there's another big win to come. It's great to have two Brits in the final."
They will face Britain's Louise Hunt and Germany's Katharina Kruger in Sunday's final after they came from 5-2 down in the final set and saved three match points to beat Dutch pair Marjolein Buis and Michaela Spaanstra.
Scotland's Gordon Reid will also be in action in the men's doubles decider after he and French partner Michael Jeremiasz got the better of Shingo Kunieda and Evans Maripa 6-1 4-6 6-2.
In the decider, Reid and Jeremiasz will take on top seeds Joachim Gerard of Belgium and France's Stephane Houdet.