TENNIS: Djokovic's French Open future uncertain after stunning loss to Fonseca

Three-time French Open champion Novak Djokovic said he was unsure if he would return to the red clay of Roland Garros next year, following his third-round defeat by Brazilian teenage sensation Joao Fonseca on Friday.

The 39-year-old Serb, who celebrated his birthday last week, fell to a rare defeat in Paris, raising questions over his future in the tournament after 22 consecutive appearances.

"I don't know," the world number four said when asked whether he would play in Roland Garros again.

Djokovic, who has been injured for three months, said he felt he had played "really good tennis" against Fonseca but felt tired at the end of what will enter records as his longest game ever played in the French Open at four hours and 53 minutes.

"A couple of times where I felt like I was barely standing on my legs towards the end of the match," the 24-time Grand Slam winner said.

It was the second time that Djokovic lost from two sets up, with the other also coming at Roland Garros, against Jurgen Melzer in 2010.

Should Djokovic choose to return, he would join a short list of players featuring in the French Open at 40, a feat achieved by few in the Open Era.

-Sybille de La Hamaide/Reuters