Wozniacki retires hurt in Bastad
World number one Caroline Wozniacki was forced to retire injured from her second round match in Bastad with a shoulder injury.
The Dane won the first set against local player Sofia Arvidsson of Sweden 6-2 but suffered problems early in the second.
After trying a couple of almost underarm serves she then called for the trainer before conceding the match while 1-0 down in the second.
Arivdsson will now face Maria Jose Martinez in the quarter-finals.
Pennetta will now face Barbara Zahlavova Strycova after the Czech player won a three set battle with Anastasiya Yakimova.