Aptos (California), July 18 - India's Somdev Devvarman defeated South African Davis Cupper Izak van der Merwe 6-4, 6-2 to enter the semi-final of the $75,000 Association of Tennis Professional (ATP) Challenger.

The win will stand in good stead for Somdev, who will spearhead India's singles challenge against South Africa in the Davis Cup World Group play-off in Johannesburg.

The sixth-seeded Somdev next plays big serving Australian Chris Guccione, who overcame stiff resistance from third-seeded American Wayne Odesnik 7-6(5), 2-6, 76(2).

Somdev and his Filipino partner Treat Conrad Huey had already lost in the doubles first round.

India's Harsh Mankad and his American partner David Martin will play third-seeded Australian pair Carsten Ball and Guccione in the doubles semi-finals.