American Vincent Spadea became the latest seed to tumble from the AAPT tennis championships when beaten by an unheralded compatriot on Thursday.

Spadea, the tournament's eighth seed, was upset by fellow American Brian Vahaly in a second round encounter at Memorial Drive.

Spadea's unexpected exit means only two seeds have progressed into the quarterfinals in a blow to organisers hoping to lure crowds to the event.

Vahaly, ranked 146 in the world at the end of last year, was an impressive winner in straight sets, 7-6 (7-1) 6-2.

In his first appearance at the annual Adelaide tournament, Vahaly faces a probable quarterfinal clash against Dutchman Richard Krajicek.

Spain's sixth seed Alberto Martin also advanced today with an accomplished 7-5 6-1 victory over rising French teenager Richard Gasquet.

Martin joins Argentinian fifth seed Mariana Zabaleta as the only players from the eight seeds still alive in the championships.

Also today, Belgium qualifier Kristof Vliegen continued the trend of shock results when trouncing Great Britain's Arvind Parmar 6-2 6-2 in a second round match which lasted just 51 minutes.

Among the bigger names to fall from the tournament have been top seed Wayne Ferreira, ousted in the first round, Belarussian Max Mirnyi and Swede Thomas Enqvist.

Australians Scott Draper, Adam Kennedy and Todd Reid were all defeated in opening round matches.

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