Health woes build for Serena Williams

Serena Williams' absence from tennis could stretch to almost a year after two new health scares -- a blood clot in her lungs followed by a hematoma -- added to her injury woes.

Agents for Williams verified that she underwent emergency treatment Monday and was hospitalized for two nights. The blood clot, known as a pulmonary embolism, was discovered last week.

Williams, winner of 13 Grand Slam titles, hasn't played an official match since winning Wimbledon July 3. She cut her right foot on broken glass at a restaurant shortly after the victory, and her comeback has been repeatedly delayed by complications.