Henin and Serena through in Miami
Henin won her only title of the year so far in Antwerp
Belgium’s Henin, was playing for the first time since defeat by Francesca Schiavone in Dubai last month, saw off Germany’s Kerber 6-4 6-2.
Williams thrashed Edina Gallovits 6-1 6-2, while Svetlana Kuznetsova beat Yung-Jan Chan 6-1 3-6 6-0.
Novak Djokovic and Rafael Nadal are in action later on Friday.