Watson gave Britain a 1-0 lead when she beat Petkovic 6-2, 7-6 (3) in singles, coming back from 5-1 down in the second set.
But Zverev leveled for Germany when he beat Evans 6-4, 6-3, sending it to the mixed doubles decider which was played under the Fast4 format.
It was Germany’s first win of the tournament, an ITF invitational event which offers no ranking points but has prize money and provides preparation for the upcoming Australian Open. Britain finished 0-3.
Later Friday, Roger Federer and Belinda Bencic were scheduled to lead Switzerland against Kristina Mladenovic and Richard Gasquet of France, with the winner playing the United States team of Coco Vandeweghe and Jack Sock in Saturday’s final.
Original author: Ashley Ndebele