Unseeded Lee Childs of Great Britain pulled off a major upset when he stunned top seed Michal Mertinak of Slovakia, winning 6-4, 6-2, to sail into the quarter-finals of the US $25,000 ATP Challenger series at Tumkur, Karnataka, on Thursday.

Lee, who held the upper hand from the word go, needed just 69 minutes to send Michal, ranked 190 in the world, packing out of the tournament.

The pre-quarter-finals day virtually belonged to unseeded players, as at least four seeds, including Mertinak, bowed out of the tournament.

Drawing inspiration from his British compatriot, Lee Martin, quelled the challenge of sixth seed Marcello Craca of Germany in a gruelling contest, lasting three hours.

Martin defeated Marcello 6-2, 6-7 (10-8), 7-6 (7-5) to ensure a berth in the quarter-finals.

Philipp Kohlschreiber of Germany scored another upset, beating third seed Rik De Voest of South Africa 6-4, 7-5 while Stephane (SUI) outplayed seventh seed Oliver Marach (AUT) 6-2, 6-0 to move into the quarter-finals.

The lone seeded player to win was fifth seed Michal Tabara of Czechoslovakia. His opponent, compatriot Ota Furarek, conceded the match as his lower back pain aggravated when play was in progress in the second set.

Michal had won the first set at 7-6 (7-5) and both players were level three-all in the second set when Ota chose to withdraw.

The Indian challenge in the singles ended today, with Harsh Mankad making his exit, losing to Marco Baghdatis of Cyprus 6-4, 7-5.

Dieter Kindlmann of Germany defeated Michal Przysiezny of Poland 6-4, 6-0 to reach the quarter-finals.

Francesco (Italy) joined the quarter-finalists after defeating compatriot Leonardo Azzaro 7-6 (7-2), 6-2.

The lone Indian left in contention is Prakash Amritraj, in the doubles.

Amritraj, partnering South Africa's Rik De Voest, defeated the British duo of James Auckland and Lee Childs 6-3, 6-7 (7-3), 7-6 (7-4) to enter the quarter-finals.