World number four Rafa Nadal has confirmed he will return to competitive action at the Mubadala World Tennis Championship in Abu Dhabi at the end of December after six months out with a knee injury.

The 11-times grand-slam singles champion has not competed since a shock defeat to Czech Lukas Rosol in the second round at Wimbledon in June.

The Spaniard was later diagnosed with a partial tear of the patella tendon and an inflammation in his left knee and was unable to defend his Olympic title at the London Games. He also missed the U.S. Open and the season-ending World Tour championships before returning to the practice court on November 20.

"Can't wait to get back on court in Abu Dhabi at the end of the month," the 26-year-old wrote on his Facebook page on Tuesday.

"I won the Mubadala World Tennis Championship in 2010 and 2011," he added. "Would love to get my hands on the trophy again this year!"

Nadal is due to play either world number three Andy Murray of Britain or ninth-seeded Serbian Janko Tipsarevic on December 28 at the event in Abu Dhabi, which is not part of the ATP Tour.

World number one Novak Djokovic of Serbia, fifth-ranked Spaniard David Ferrer and number six Tomas Berdych of Czech Republic are also taking part.

Nadal said this month he was hoping to be back to full fitness in time for the clay season, when he will be chasing an eighth French Open title on his favoured surface after winning a record seventh Roland Garros crown in May.