Tennis: Top seed Del Potro out of Lisbon Open with illness

Top seed Juan Martin del Potro has withdrawn from next week's Lisbon Open, organisers confirmed on Friday.

Officials said they received word from the player's agent that he was ill with a stomach virus and would not make the trip to Europe.

The world number seven's absence from the 250 series tournament leaves Swiss Stanislas Wawrinka as the main draw card at the re-branded clay event.

The concurrent WTA field in Lisbon is headed by Frenchwoman Marion Bartoli and Dominika Cibulkova with three-time Grand Slam winner Svetlana Kuznetsova earning a wildcard.