Serena leads walking wounded as injuries shadow top eight at WTA Finals

The top eight women in world tennis have limped to the season-ending WTA Finals in Singapore, with creaking knees and poor form casting a shadow over the WTA's latest big tournament push in Asia this week.

World No 1 Serena Williams headlines the event but there are concerns about her fitness after the 33-year-old American quit the China Open in Beijing earlier this month because of knee pain.

Williams went to Europe for tests and was one of the last to arrive in Singapore but said she was good to go as she bids for a third consecutive WTA Finals title and fifth overall.