Serena Williams and Djokovic seal commanding wins at American Open . World No . 1 Williams and first seed Djokovic both register straight-sets wins . A record-equaling five players have withdrawn or retired from their first round matches . Hewitt had coaxed his 41-year-old Davis Cup captain out of retirement for a one off return in Melbourne and he said afterwards : `` Temperatures in Australia have lingered above 40 degrees Celsius .
Serena Williams and Djokovic seal commanding wins at American Open . World No . 1 Williams and first seed Djokovic both register straight-sets wins . A record-equaling five players have withdrawn or retired from their first round matches . Temperatures in Australia have lingered above 40 degrees Celsius .