I could play on until I am 40, says Djokovic

In bad news for his opponents, 12-time Grand Slam winner Novak Djokovic said on Friday that he may continue his astonishing career until the age of 40.

Speaking after securing a place in the Qatar Open final against Andy Murray, Djokovic said he would play on for as long as he could.

Asked if could still be on tour aged 40, the Serb replied: "Why not? You're going to see a lot of me in the future."

Djokovic, who turned professional in 2003, celebrates his 30th birthday in May this year.

Earlier this week in Doha he played against 38-year-old Radek Stepanek, one of the oldest players on the ATP tour.

After beating the Czech veteran, Djokovic said he was "excited" about the longevity of Stepanek's career.

"It shows me that I can have as long a career as he has. If he can do it, I can do it, too," said Djokovic.

The oldest player currently in the top 20 is 37-year-old Ivo Karlovic.

The Croat is currently ranked number 20 in the world and, notably, was the last player to Djokovic in Doha in 2015.

The oldest ever winner of a Grand Slam in the Open era is Ken Rosewall, who won the Australian Open in 1972 aged 37.