Seeds had a tough day at the Kingfisher Airlines Mumbai Open on Thursday. Mario Ancic, Dmitry Tursunov [Images] and Tommy Robredo were stretched in the second round while eighth seed Wesley Moodie of South Africa [Images] crashed out of the tournament, losing 6-7, 6-7 to James Auckland of Great Britain.

Tursunov, who admitted that he was struggling with the humidity in Mumbai, struggled to a 6-7 (5), 6-3, 6-4 victory over Denmark's Kristian Pless. The Russian struggled with his serve and still seemed haunted by the marathon effort in the Davis Cup semi-final against the United States last week.

Crowd favourite and second seed Ancic had to counter a gritty Stefano Galvani before winning 6-1, 7-6 (6) and setting up a quarter-final clash with Austria's Stefan Koubek, while top seed Robredo survived some anxious moments before beating Germany's [Images] Michael Berrer 5-7, 6-2, 6-4 in an hour and 51 minutes.

Ancic cruised through the first set before losing the rhythm on his serve and was made to sweat on the baseline. The players traded breaks of serve in the sixth and seventh games and it looked like Galvani could take the match into the third set. But Ancic stepped up a gear in the tie-break to win it 8-6.

"I lost my serve a little bit in the second set and he was returning well. But I had to keep up the aggression and was happy to close out the match in two sets," said Ancic after the effort.

He added that a two-day gap between his first round and second round matches did not help.

Earlier in the day, Juan Martin del Potro, who caused the biggest upset of the tournament by knocking out Spain's Carlos Moya [Images], felt the effects of humid conditions and had to withdraw from his second round match due to illness.

Potro was trailing Paraguay's Ramon Delgado 3-6, 1-4 when he threw up on the court and pulled out of the match. The illness forced he and partner Juan Monaco to award James Auckland and Jamie Delgado a walkover in the doubles quarter-finals.

Koubek and third seed Tomas Berdych also progressed into the last eight. Koubek beat Devilder 7-5, 6-3 while Berdych overcame a tough challenge from Germany's Simon Greul, winning 7-6, 6-4.

The singles quarter-final line-up is:

1-Tommy Robredo (ESP) v Ramon Delgado (Par)

4-Dmitry Tursunov (Rus) v James Auckland (Brit)

6-Bjorn Phau (Ger) v 3-Tomas Berdych (Cze)

Stefan Koubek (Aut) v 2-Mario Ancic (Cro).

Thursday's results: Stefan Koubek (Austria) beat Nicolas Devilder (France [Images]) 7-5, 6-3; 2-Mario Ancic (Croatia) beat Stefano Galvani (Italy [Images]) 6-1, 7-6 (6); James Auckland (Britain) beat 8-Wesley Moodie (South Africa) 7-6 (3), 7-6 (5); Ramon Delgado (Paraguay) beat Juan Martin Del Potro (Argentina) 6-3, 4-1 (Del Potro retired); 4-Dmitry Tursunov (Russia [Images]) beat Kristian Pless (Denmark) 6-7 (5), 6-3, 6-4; 3-Tomas Berdych (Czech Republic) beat Simon Greul (Germany) 7-6 (4), 6-4; 6-Bjoern Phau (Germany) beat Gouichi Motomura (Japan [Images]) 6-3, 6-3; 1- Tommy Robredo of Spain beat Germany's Michael Berrer 5-7, 6-2, 6-4.

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