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 A record-equaling five players have withdrawn or retired from their first round matches .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 .
Serena Williams and Novak Djokovic seal commanding wins at Australian Open . World No . 1 Williams and second seed Djokovic both register straight-sets wins . A record-equaling nine players have withdrawn or retired from their first round matches . Temperatures in Melbourne have lingered above 40 degrees Celsius .