Rafael Nadal
IN PHOTO: Rafael Nadal of Spain reacts during his semi-final match against Novak Djokovic of Serbia at the Monte Carlo Masters in Monaco April 18, 2015. REUTERS/Jean-Paul Pelissier

Roger Federer of Switzerland believes that Rafael Nadal of Spain is still a very dangerous opponent at the 2015 French Open despite struggling with injuries for most of 2014 and some first round and early rounds exits in the current tennis season.

"Rafa [Nadal] for me is still the favourite at the French Open, alongside [Novak] Djokovic, who has been playing so well," Federer said in a news conference in Istanbul for the 2015 Istanbul Open, a clay court tournament. "Even though Rafa's form is not as good as in previous years, I still believe when the French Open rolls around he is going to be very difficult to beat."

Nadal is considered the modern tennis era’s clay court greatest player winning the French Open at Roland Garros nine times in his career in 2005, 2006, 2007, 2008, 2010, 2011, 2012, 2013 and 2014. However, Nadal has failed to find the Grand Slam form of late. He has struggled with injuries to his wrist in 2014 and 2015 has been an up-and-down season.

Nadal’s latest disappointment came at the 2015 Barcelona Open when he had his earliest defeat in 12 years after falling to Italian Fabio Fognini, 6-3 6-1 in the third round of the competition. Nadal also lost to Fognini in the semi-final of the 2015 Rio Open last February with a score of 6-1, 2-6, 5-7 for the Italian.

Nadal admitted in post-match interviews that he played poorly against Fognini but promised that he will keep on working to get back to top form. Nadal is currently the men’s world no. 4 "

Today is a bad day,” Nadal said after his disappointing exit in Barcelona to the tournament’s official website. “But my challenge is to get back to my best level again and I will work until that happens. I have the conviction that it will happen.”

One of the people who believe Nadal is rival Federer, who believes that Nadal will be healthy and in top-form during the 2015 French Open which is scheduled to take place from May 24 to June 7, 2015.

Email j.gloria@IBTimes.com.au to contact author.