Spaniard Rafa Nadal is keeping his expectations low ahead of his long-awaited return to competitive action in early February after seven months out of tennis with a knee injury.

The 26-year-old French Open champion has not played since losing to Czech Lukas Rosol in the second round at Wimbledon in June due to a partial tear of the patella tendon and inflammation in his left knee.

His planned return at the end of last year was delayed due to illness and he is scheduled to play on his favoured clay at three events next month, starting in Vina del Mar, Chile, on February 4 and taking in the Brazil Open in Sao Paulo from February 11 and the Mexico Open in Acapulco from February 25.

"Well I am going to play (after) a long time in a tennis tournament, professional tennis tournament, after seven months," Nadal told reporters after training on his home island of Majorca.

"The motivation, the illusion is big, so very happy to be back in the competition but just you know, with patience to know how the knee will answer after a long time without the top level," he added.

"The most important thing for me is the knee...that I can support the pain of the knee and then if I am able to play these three tournaments in a row I think it will work very well for me because I will have three important weeks to prepare for the rest of the season.

"I know that the first three tournaments are going to be difficult in terms of results but I am going to try everything. I will need a few weeks to see how things improve."

Nadal's absence deprived tennis of one of the "big four" who have dominated the sport in recent years.

During his spell on the sidelines, Serbian world number one Novak Djokovic won the 2012 World Tour finals and the Australian Open, number two Roger Federer of Switzerland won Wimbledon and third-ranked Briton Andy Murray the US Open and Olympic gold.

In the latest ATP rankings published on Monday, Nadal, who won a record seventh Roland Garros crown in May, slipped below compatriot David Ferrer to number five.

Fifth-seeded Roberta Vinci was bounced out of the Open GDF Suez when she was beaten by Mona Barthel of Germany 4-6, 6-1, 6-3 in the second round Wednesday.

Vinci struggled in the second set, losing two of her service games. Matters worsened for the Italian when Barthel immediately broke serve in the third set.

Ranked 16th, Vinci broke back but the 45th-ranked Barthel broke twice more to take the match.

Barthel will meet third-seeded Marion Bartoli of France or Christina McHale of the United States in the quarterfinals.

Sixth-seeded Lucie Safarova of the Czech Republic recovered from an early scare to beat Lourdes Dominguez Lino of Spain 2-6, 6-1, 6-1.

Safarova next faces Frenchwoman Alize Cornet.

- AP