World number three Novak Djo-kovic had to shake off a determined challenge from Fernando Verdasco to cla-im a 6-7, 6-3, 6-3 win over his unseeded opponent in the second round of the Madrid Masters on Wednesday.

The 20-year-old will face Juan Carlos Ferrero in the last 16 after the Spaniard got the better of compatriot Carlos Moya 7-6, 6-4 in a duel between former world number ones.

In an earlier match, wildcard Feliciano Lopez delivered a blow to seventh seed David Ferrer's bid to qualify for the Shanghai tournament with a 7-6, 7-5 win on centre court.

Sixth seed James Blake's hopes of earning a place at Shanghai also suffered a setback when he lost to Mario Ancic 6-3, 6-4.

Ninth seed Thomas Ber-dych also exited the $2.2 mi-llion hardcourt tourney, Argentine David Nalbandian coming from a set down to claim a 4-6, 6-4, 7-6 win over the world number 10.

Last year's losing finalist Fernando Gonzalez had to battle hard to record a 7-6, 7-5 win over the combative Nicolas Almagro in his match.

Argentine Guillermo Ca-nas also had to battle hard to snatch a 6-3, 3-6, 7-5 win over compatriot Agustin Calleri and earn a third-round tie against Federer.

Big serving Croat Ivo Karlovic hammered 20 aces to see off lucky loser Oscar Hernandez in straight sets 7-5, 6-2.

Mauresmo beaten

Ukraine’s Alona Bondarenko stunned former world No 1 Amelie Mauresmo in the second round of the Zurich Open on Wednesday.

Bondarenko scored a 2-6, 6-4, 6-1 win over the Frenchwoman.

On Tuesday, local favourite Patty Schnyder eased into the second round after sixth seed Serena Williams retired injured at 6-0, 3-0 down. Ninth seed Marion Bartoli also struggled before overcoming China’s Peng Shuai 6-7, 6-0, 6-1 to set up a second round meeting with Dutch wildcard Michaella Krajicek.