Britain's Jamie Murray and Brazilian partner Bruno Soares lost to Dutch duo Wesley Koolhof and Matwe Middelkoop in the final of the Sydney International.
Murray and Soares won the title last year in only their second tournament as a doubles pairing.
But the top seeds were beaten 6-3 7-5 on Saturday, as Koolhof and Middelkoop won a third ATP trophy.
British number three Dan Evans will face Gilles Muller from Luxembourg in the singles final at 08:30 GMT.
Evans, the world number 67, is playing in his first ATP Tour final.
Elsewhere, American world number 23 Jack Sock won the final of the Auckland Classic with a 6-3 5-7 6-3 victory over Portugal's Joao Sousa.