(CNN) -- Former world number one Lleyton Hewitt continued his fine run at the U.S. Clay Court Championships with a straight sets win over Sergio Roitman of Argentina 6-1 6-3 in Houston.
The emphatic victory in just under an hour took the Australian into the quarterfinals at River Oaks Country Club as he continues his comeback after hip surgery last year.
The 28-year-old converted all of his seven break point opportunities in the second round match and shrugged off the loss of his own service twice in the second set as Roitman attempted to fight back.
It is the third time this season he has reached the quarterfinals, his best a run to the semis in Memphis.
The seeded upsets also continued on Wednesday as third-ranked Jurgen Melzer of Austria went down 6-4 6-0 to Wayne Odesnik of the United States and fourth seed Jeremy Chardy crashed 6-1 6-0 to Guillermo Garcia-Lopez of Spain.
Defending champion Marcel Granollers of Spain, the sixth seed, is the only seeded player left in the tournament.
Top two seeds James Blake and Mardy Fish, both of the United States, were eliminated in first round matches.
On the WTA Tour, top seed Nadia Petrova beat 14-year-old American Madison Keys 6-3 6-2 in the second round of The MPS Group Championships in Florida.
It gives Russian Petrova a quarterfinal match against seventh seed Alona Bondarenko of the Ukraine.
Bondarenko beat her younger sister, Kateryna, 4-6 6-4 6-3 to go through to the last eight.