Serena Williams of the US reacts during her women's singles match against Roberta Vinci of Italy at the French Open tennis tournament at the Roland Garros stadium in Paris, June 2, 2013. [Photo/Agencies]

PARIS - Ask her to describe the way she plays and Serena Williams has a one-word response - fierce.

She is unlikely to hear a word of disagreement from Roberta Vinci after the Italian was beaten 6-1 6-3 in the fourth round of the French Open on Sunday, a result that keeps Williams on course to win a first Roland Garros title since 2002.

The match hammered home the inescapable truth that there is no substitute for raw power in the modern women's game as Williams, whose array of shots could blow holes in concrete, ably demonstrated by out-muscling the canny Vinci.

The Italian found out that as you head into the second week of a Grand Slam, you need at least one weapon in your armoury that can put your opponent on the back foot.

As it happens, Williams has a whole arsenal at her disposal and wrapped up victory for the loss of only four games, to take the total she has conceded in the entire tournament to 10.

Asked for a word to describe Vinci, a doubles specialist who relies more on her wiles to stay afloat, Williams replied: "Tricky".

Her own epithet was more emphatic.

It was certainly a fearsome display that she put in to complete her 28th straight victory and underline her title potential.

She coped better with the blustery conditions on Philippe Chatrier Court and broke three times to take the first set.