Sunil Kumar Sipaeya set up a quarter-final clash with second seed Aisam-ul Haq Qureshi of Pakistan after his opponent and compatriot Rohan Bopanna retired during their second-round match of the $ 50,000 SAIL [Get Quote] Open Challenger series tournament in New Delhi on Wednesday.

Sipaeya led 6-4 1-6 4-2 before sixth seed Bopanna, who took a medical break during the second set, pulled out complaining of a back strain.

Sipaeya now takes on last week's Challenger winner Qureshi, who got a walkover into the last-eight stage from German Dieter Kindlmann.

The 24-year-old Sipaeya was on a roll from the start and once again displayed some fine strokeplay from the baseline. He was quick to pounce on the very first break points he got in the seventh game of the first set, albeit with a bit of luck going his way.

A low backhand from Sipaeya bounced off the net to land awkwardly in front of Bopanna who miscued it to hand his opponent three break points. Bopanna then buried a backhand into the nets as Sipaeya went a break up.

Leading 40-0 in the 10th game, Sipaeya sent down an ace to close the set in his favour.

A struggling Bopanna called for medical aid for his troubling back at the start of the second set and it seemed to
have worked as he broke Sipaeya twice to take a 5-1 lead before winning the set on his serve to take the match into a third.

Bopanna, however, was unable to cope with his niggling back and within no time Sipaeya had gone 3-0 up with his deep serve and swift coverage of the baseline.

Both the players exchanged a break of serve before Bopanna decided to call it quits from the match.

Meanwhile, in a major upset fourth seeded Adrian Menendez of Spain crashed out of the tournament after losing 2-6 2-6 to Czech Republic's Tomas Cakl.

Frenchman Sebastian De Chaunac staged a remarkable comeback to beat Russian Pavel Chekhov 6-4 7-6 (11/9) 7-5 in a marathon second-round encounter.