JOHANNESBURG (AFP) - Young South African Izak van der Merwe and French journeyman Sebastien de Chaunac mocked the world rankings Wednesday to set up a SA Tennis Open second-round showdown.

Giant Van der Merwe won successive tie-breakers to eliminate in-form German Benjamin Becker, who was 163 places above his opponent on the ATP list released Monday.

And De Chaunac belied his ranking of 225 to topple Spanish third seed Marcel Granollers 7-5, 7-6 on a near-deserted outside court as the small crowd who braved wet, chilly conditions huddled around the Montecasino centre court.

In other matches on a rain-delayed third day of the first ATP tournament in South Africa for 14 years, second seed David Ferrer and eighth seed Marcos Baghdatis triumphed in straight sets and will meet in the quarter-finals.

Spaniard Ferrer saw off German Simon Greul 6-3, 6-4 while Paris-based Cypriot Baghdatis survived a spirited challenge from South African 'wildcard' Raven Klaasen for a 6-3, 7-5 win.

Van der Merwe always had the edge over the much shorter Becker, who arrived in Johannesburg fresh from victory in a second-tier Challenger event in Germany last weekend.

But despite delivering nine aces, the South African from the western Cape university town of Stellenbosch believes his service must improve to see off the challenge of De Chaunac.

The 31-year-old Frenchman came through a three-match qualifying programme to reach the Australian Open and made the second round before bowing to American James Blake.

He needed wins against two South African opponents in Johannesburg just to secure a first round slot and was an outsider against Granollers, ranked 47 and the second youngest Spaniard in the top 100 after superstar Rafael Nadal.

But De Chaunac proved his Melbourne form was no blip on the ATP radar screen with a courageous, service-driven display that earned him a deserved victory on a court that was a carpark just three months ago.