PARIS (REUTERS) - Four-time Grand Slam champion Kim Clijsters plans to come out of retirement next year after a seven-year hiatus, the 36-year-old Belgian said on Thursday (Sept 12).

The decision to return to the WTA Tour marks her second U-turn to tennis after first retiring in 2007.

"I don't really feel like I want to prove something," Clijsters said on the WTA Insider Podcast. "I think for me it's the challenge.

"The love for the sport is obviously still there. But the question is, am I capable of bringing it to a level where I would like it to be before I play at a high level of one of the best women's sports in the world.

"I want to challenge myself and I want to be strong again. This is my marathon."

Two years after winning her first Slam at the 2005 US Open, an injury-plagued Clijsters decided to quit the game at the age of 23 to start a family, returning two years later to claim her second US Open as an unranked player in only her third tournament back.

Clijsters defended her title at Flushing Meadows the following year and then won the Australia Open in 2011 en route to topping the world rankings for the first time since 2006.

With 41 titles to her name, Clijsters hung up her racket after the 2012 US Open and later worked as a tennis commentator.

Clijsters said she has been considering a return to the tour for the past two years.

"I feel like I've had more energy these last six months or so than I've had in the last two years because I'm taking care of myself better," Clijsters added.

"Even if I don't make it, this whole process has been so worth it for me to get back into a good routine."