Prakash Amritraj shocked fifth seed Brunc Echagaray of Mexico to advance to the semi-finals of the US $75,000 Comerica Challenger Series Tournament in Aptos, California.
The wildcard entrant won 6-3, 1-6, 6-3 to set up a clash with American Donald Young, who also caused a major upset by beating fourth seed Alex Kuznetsov 7-5, 6-4 in Friday's other quarter-final.
Elsewhere, third seeds Rohan Bopanna and Aisam-ul Haq Qureshi of Pakistan sailed into the US $25,000 Manchester Trophy Challenger series Tournament final with a 6-4, 7-5 victory over the Australia's Andrew Coelho and Adam Feeney.
The Indo-Pakistani pair will take on the Dutch-Swedish duo of Jesse Huta Galung and Michael Ryderstedt in the summit clash.
Galung and Ryderstedt also beat an Australian team, of Luke Bourgeois and Alun Jones, 6-3, 7-5.
Bopanna and Qureshi are pitted against each other in the singles quarter-finals. While Bopanna is seeded seventh, Qureshi is the tournament's second seed.
