Newport, Rhode Island, USA, 12 July 2012 | AAP-AP

Lleyton Hewitt continued to build his grasscourt form in preparation for the London Olympics with a three-set win over American qualifier Tim Smyczek in the second round of the ATP Hall of Fame Tennis Championships on Wednesday.

The former world No.1 scored a 6-4 2-6 6-1 victory at Newport in Rhode Island to advance to a quarterfinal encounter with Israeli Dudi Sela, who beat American Sam Querrey 5-7 7-6(6) 6-2.

Hewitt will compete in the singles at the London Games later this month and the 31-year-old is aiming for rapid improvement as he looks to perform well on the same grasscourts on which he won the Wimbledon title in 2002.

Hewitt was defeated by Frenchman Jo-Wilfried Tsonga in the first round of Wimbledon two weeks ago which followed another opening-round exit to Croatian nemesis Ivo Karlovic on the grasscourts of Queen’s in London.

In other results, top seed and defending champion John Isner also advanced to the quarter-finals with a 6-2 7-6(2) win over Frenchman Nicolas Mahut.

Two years ago, the pair played for 11 hours and five minutes at Wimbledon in the longest match in tennis history, with Isner finally getting a 70-68 fifth-set victory.

This one didn’t have nearly the drama as Isner used his overpowering serve to take charge and secure the win in 78 minutes.

Second seed Kei Nishikori of Japan also advanced to the last eight, outlasting Olivier Rochus from Belgium 6-7(6) 6-4 6-2.

Rajeev Ram beat fellow American Michael Russell 7-6(6) 6-3 and Izak Van Der Merwe of South Africa beat American Jack Sock 6-4 6-4.