Rafael Nadal and Caroline Wozniacki have been crowned the International Tennis Federation world champions for the year 2010.

Wozniacki, the 20-year-old from Denmark, ousted 13-time Grand Slam winner Serena Williams for the crown, despite not winning a single grand slam in the year. However, she had won an impressive six tournaments in 2010.

She said, To be listed with all the former world champions is something I'm really proud of.

ATP World number one, Rafael Nadal, who won three grand slams - the French and US Opens and Wimbledon - during the year, regained the crown from World No. 2 Roger Federer.

The crown caps an amazing year for Nadal who overcome a persistent knee problem to win a 5th French Open and a second Wimbledon title.

His US Open triumph in September made him the the youngest player ever, and only the seventh in history, to complete a career Grand Slam. He said, It is an honour to be named world champion for the second time, he said.

After a difficult year in 2009, it was an amazing feeling to regain the number one ranking and finally win the US Open. My goal all the time is to keep improving and be a better player each year than I was the previous year.