Laura Siegemund was hailed for her mental fortitude in the face of 10,000 Brazilian fans as the German women progressed to the Billie Jean King Cup Finals. Siegemund won both her singles matches in the weekend qualifier in Sao Paulo to give Germany a 3-1 win over Brazil in the women’s team tennis tournament. The 36-year-old secured the decisive third point for Germany with a 6-1, 2-6, 6-3 win in the fourth singles rubber against Carolina Alves. “It was an absolute cauldron for Laura,” team captain Rainer Schüttler said about the atmosphere in the Arena Ginásio Ibirapuera. “She was mentally str…