Top seed Serena Williams began the defence of her Rome Masters title with a comfortable 6-2 6-2 win over Andrea Petkovic this afternoon.

The two-time champion broke her German opponent twice at the start to race out to a 4-0 lead before seeing out the set without offering Petkovic a chance of a break back.

The second set started in similar fashion to the first as Williams broke Petkovic twice, but this time the German did fight back, pegging the American back to 3-2.

Williams got back on top straight away and won the next three games to take the set and match in just under 80 minutes.

The world number one, who is said to be struggling with a thigh injury, next faces Varvara Lepchenko in the third round.