Rafael Nadal is fretting over his troublesome left knee as he attempts to win his eighth straight Monte Carlo Masters and end a title drought dating to last year's French Open.

Nadal pulled out of his semifinal against Andy Murray at last month's Sony Ericsson Open. He then received treatment for a knee tendon problem after having already skipped a chunk of the season to rest his knees following the Australian Open.

"It's OK now. (I need) time to see how it is at the top level, run without thinking about the knee, when I put all my pressure on the knee," Nadal said Monday. "It's the start of the clay-court season for me, and hopefully it will work well."

But the 10-time Grand Slam champion expects to be rusty in his second-round match against Finland's Jarkko Nieminen on Wednesday. He started practicing only four days ago.

"I's not enough after 15 days off without chances to practice a lot because I couldn't move my knee," the 25-year-old Spaniard said. "I'm a little bit scared, but seems like today I am able to practice with no (problems)."

Nadal rested his knee after the Australian Open, where he lost his seventh straight tour final to top-ranked Novak Djokovic. He didn't play again until several weeks later at Indian Wells, where he lost in the semifinal to Roger Federer in straight sets.

At the following tournament in Miami, his left knee flared again. He withdrew hours before he was to play Murray.

"It's not easy to explain, in English especially. Even in Spanish it will be difficult. I had a little bit broke in the tendon on the top, but especially behind the knee," Nadal said. "I did (have an injection). I did the treatment two times."

He is relieved to be back on clay, where there is less stress on his knees.

"The worst surface for the players is the hard," Nadal said. "I believe we are wrong in the tournament(s) to play more and more on hard (courts), and less and less on clay and grass."

Since 2005, Nadal has won at Monte Carlo and Roland Garros every year except '09.

"It's special to come back to a place where I have more success than (anyone)," said Nadal, who has won 37 consecutive matches in Monte Carlo and holds a 39-1 record. "The conditions worked for me in the past, I always played my best tennis here, I believe."

The six-time French Open champion, who could face Djokovic in the Monte Carlo final, is playing down his title slump.

"I didn't win a title, but how many final I played?" asked Nadal, who has 46 career titles to 73 for Federer. "I am doing my calendar to try and win important titles, or the most important titles on the tour, to try to be healthy as long as I can."