Kim Clijsters is at a loss as to how to follow her remarkable US Open success but she is looking forward to trying.

The 26-year-old Belgian former world number one came out of a 27-month retirement last month and just three tournaments into her comeback, 18 months after becoming a mother, won a grand slam championship at Flushing Meadows.

Clijsters beat both third seed Venus Williams and defending champion Serena Williams en route to the final as well as 14th seed Marion Bartoli and 18th seed Li Na before taking the title on Sunday with a 7-5 6-3 victory over number nine seed Caroline Wozniacki.

"I don't know how I'm going to top this, but it's a challenge," Clijsters said.

"It's a challenge now at each tournament you play to try to show your best tennis and to stay in good shape.

"It's something that I'm going to be really focusing on, to think wisely about my schedule and pick my tournaments and whatever I play and whenever I play, just really try to peak at certain situations.

"So I think it's something that now with my coach, my physio and everybody, that's something that we're just going to keep focusing on, is making sure that I still work hard and everything.

"But also, they also know how important it is to have that family life at the same time. So I'm not playing next week or anything. I just want to go home and relax for a little bit."

Clijsters, who won her only previous grand slam title at the 2005 US Open and had not played in the New York grand slam since, retired in May 2007, married basketball player Brian Lynch two months later and gave birth to daughter Jada in February 2008.

She had been preparing seriously for a comeback since the start of the year, working with coach Wim Fissette and physical trainer Sam Verslegers.

Clijsters got herself fit and match ready, playing an exhibition with Tim Henman, Andre Agassi and Steffi Graf to mark the opening of the new roof over Wimbledon Centre Court and then returning to the WTA Tour in August.

Just 14 matches later she became US Open champion, watched by husband Lynch and daughter Jada.

"What a story it is," Fissette said. "Kim having a baby and coming back now, playing a final in her first grand slam, her third tournament. That sounds like a fairytale."

Verslegers said Clijsters had been badly out of shape when she had begun working with him.

"We didn't set goals but she knew what the main goal was," he said. "She could run 30 minutes but that was about it.

"She was not in a great condition. The first time she ran her heartbeat went up to 160 (beats per minute) even at 10 kilometres an hour.

"She was overweight so it was really a start from zero."

When asked about the toughest part of returning to the tour, Clijsters concurred with Verslegers.

"The fitness, definitely," she said. "I think also the mental part of when I was hitting the ball. I was hitting the ball well when it was coming towards me, but just making that switch of knowing that my body is not in the same shape as what it used to be, and that took a lot of time.

"I had a good feeling a few weeks into my practice sessions. I started hitting the ball really well and hitting the ball really clean, but it was just the movement and reading the game and everything that was missing.

"So mentally I really had to just tell myself, 'Okay, Kim, you're starting from zero here'.

"This is not a little break that I had in between tournaments or anything. This is really kind of starting from zero and re-teaching my body again and knowing how to work in tennis conditions.

"So that was probably the hardest in the beginning. No swearwords like Serena but a lot of swearing going on."