Defending champion Jelena Jankovic suffered a quarter-final upset at Stuttgart's WTA tournament yesterday as unseeded Italian Flavia Pennetta ignored a lack of sleep to snatch a 2-6, 6-4, 6-4 victory.

Having only nodded off at 3 am yesterday morning after her second-round game against Nadia Petrova finished just before midnight, Pennetta rallied from losing the first set to dump out Jankovic and take her semi-final place.