MELBOURNE, Australia (AFP) — Novak Djokovic and Andy Murray hit top gear yesterday as warhorse Lleyton Hewitt capitalised on Andy Roddick’s retirement to reach the third round.

Serena Williams was also at her destructive best with Petra Kvitova, the only top seed given trouble on day four. And Hewitt was handed easy passage when Roddick strained a hamstring, ending the clash of the old stagers.

Djokovic expended little energy in his 6-3, 6-2, 6-1 hit-out against Colombia’s Santiago Giraldo as he speeds towards an expected semi-final with Murray, his victim in last year’s title match.

Two-time finalist Murray raced through the first set in just 23 minutes as he beat France’s Edouard Roger-Vasselin, 6-1, 6-4, 6-4.

Williams brought up her 500th career win, against Barbora Zahlavova Strycova, to keep up her record of reaching the third round in every grand slam she has entered apart from her debut, in Melbourne in 1998.

Second seed Kvitov kept her frustrations in check to survive a mid-match lapse, 6-2, 2-6, 6-4.