Though there are not many changes to the current ATP rankings, Roger Federer is closing in on Rafael Nadal at the No. 2 spot.

Federer, a 16-time Grand Slam champion, is just 335 points away from Nadal, who holds second place with 9215 points in ranking, as of Monday.

Nadal is definitely in an advantageous position at the No. 2 spot, while fighting for his eight-straight Monte Carlo Masters title this week at Monaco.

Federer has withdrawn from the Monte Carlo tournament, as the Swiss star has taken a break from the game. He will return to action at the Mutua Madrid Masters next month at the Park Manzanara in Spain.

Nadal needs to win the championship this week to secure his No. 2 spot in the ATP rankings. The journey will not be easy for the Spaniard, as he is bothered by knee ailments.

Nadal, who has not won a tournament for 10 months and has lost to Novak Djokovic in seven successive finals said, "It's OK now, I need time to see how it is at the top level, to run without thinking about the knee, when I put all my pressure on the knee. It's the start of the clay-court season for me, and hopefully it will work well.

"I started to practice four days ago, it's not enough after 15 days off without chances to practice a lot because I couldn't move my knee. I'm a little bit scared, but seems like today I am able to practice with no (problems)," he said.

Djokovic still has a firm grip on the No. 1 spot with 12,670 points.

John Isner is now the top American player for the first time and climbed to a career-high ranking of No. 9 after replacing Mardy Fish, who has skidded to No. 10.