The defending Hopman Cup champions the United States and hosts Australia have lost their opening matches in the annual tennis event.
The Americans were beaten by Slovakia, while the Australia went down to Germany.
Despite the loss, the Australian player Lleyton Hewitt says he was encouraged by his own performance in his first match since undergoing hip surgery in August.
Russia and France won their Group B ties at the weekend.
The winners of each group will contest Friday's final.