Stockholm, Sweden -- (Sports Network) - Reigning five-time U.S. Open champion Roger Federer decided to pull out of next week's Stockholm Open, citing a need to rest.

"I need to get a proper rest and get strong again so that I am 100 percent fit for the remainder of the year or next year," the world No. 2 Swiss superstar said.

The 27-year-old Federer is a 13-time major titlist, including a fifth straight U.S. Open title last month. The Olympic doubles gold medalist lost the world No. 1 ranking to Spanish stalwart Rafael Nadal in August, as Nadal topped the Swiss superstar in this year's French Open and Wimbledon finals.