Breaking News: Serena Williams Suffers Pulmonary Embolism

Tennis champion Serena Williams underwent emergency treatment on Monday for a blood clot in her lungs. 

It was reported to People Magazine that Williams, 29, "underwent emergency treatment for a hematoma suffered as a result of treatment for a more critical situation," and is being treated at a Los Angeles-area hospital.

Williams, who has won 13 singles Grand Slam titles, has not played in a match since winning Wimbledon last July. She has been sidelined by two operations on her right foot after getting cut by glass at a restaurant.

Doctors are monitoring her situation, but it is unknown whether or not Williams will be able to return to tennis any time soon, if at all.

Williams has suffered many injuries throughout her career as of late, and while she has many other successful ventures, one has to wonder if this is the end of the line for Williams and her professional tennis career.

Williams has fallen to No. 11 in the world rankings during her extended layoff, but was said to be preparing to return to training soon. This may change that, but it is not known by how much.

Along with her 13 Grand Slam titles in singles, Williams has won another 12 with her sister, Venus, in doubles play. She also won two in mixed-doubles action.

Williams will go down as perhaps the greatest women's tennis player of all time. It is just unknown whether or not she will be able to make a full return to the court and improve upon her already impressive numbers.