World number three Maria Sharapova will compete in her eighth WTA Finals next month in Singapore after officially qualifying this week, the women's tennis governing body said on Thursday.

The 28-year-old Russian, who missed the U.S. Open because of injury, won the event on her debut in 2004 and has since reached the final twice in 2007 and 2012.

Grand-slam chasing Serena Williams, winner of the last three WTA end-of-year tournaments, and Romania's Simona Halep have also booked their tickets for the Oct 23-Nov 1 event.

Five more places are still available.