In the women's singles, 34-year-old veteran pro Marie Pinterova of Hungary pulled a major upset by beating top-seeded Ivanna Madruga of Argentina, 6-1, 6-4 to advance to the semifinals.
Lendl, 20, who beat Swedish tennis wizard Bjorn Borg to win the Swiss Indoor Championship Sunday, came from behind to beat Peter Rennert of the United States, 7-5, 6-0.
Lendl rallied from a 5-1 deficit to take the first set. He had no trouble winning the second set.
Second-seeded Eliot Teltscher of the United States routed countryman Bruce Manson in straight sets, 6-3, 6-3, while Mel Purcell, seeded third, turned back defending champion Terry Moor, 6-2, 6-1.
Ater winning the first set 6-3, Norback was trailing 0-1 in the second set when Mottram withdrew, giving Norback the the final semifinal spot.
Madruga, 19, told newsmen 'my legs did not move. I could not have enough training here because of rain.'
In other women's quarterfinal matches, American Dana Gilbert beat Heidi Eisterlehner of West Germany, 6-4, 3-6, 6-4; Merida Gregory of Australia downed Julie Harrington, U.S., 6-3, 6-3; and Borg's Romanian wife, Mariana Simionescu ousted China's Yu Liquao, 6-4, 6-3.
