BREE, Belgium — Kim Clijsters will return to professional tennis after two years in retirement, saying she has regained the competitive hunger that led to the No. 1 ranking.

"I still have that craving," the 25-year-old Belgian said Thursday. "I look forward to the challenge."

Clijsters, who retired in May 2007 to get married and start a family, announced her comeback at the tennis facility where she has been practicing. She plans to enter the U.S. Open, which begins Aug. 31 — her first competition at Flushing Meadows since winning her only Grand Slam singles championship there in 2005.

She asked for a wild card into the U.S. Open, along with WTA hard-court tournaments in Cincinnati and Toronto earlier in August.

"I want to be back at my peak as soon as possible, but I know that is not logical to ask that," Clijsters said. "I will have to take it match by match."

The U.S. Tennis Association is setting aside a spot in the main draw for Clijsters, who won 34 career singles titles overall and was the runner-up in four major finals.

"We have been in contact with Kim regarding her comeback and have committed a 2009 U.S. Open wild card to her," tournament director Jim Curley said. "As a past U.S. Open champion and former world No. 1, Kim has been a great ambassador for our sport. We are excited about Kim's return to tennis and look forward to welcoming her to New York this summer."

Rising to the top at the same time as fellow Belgian Justine Henin — who also retired early — Clijsters held the No. 1 singles ranking for 19 weeks.

"I am not coming back to lose in the first rounds," she said. "Otherwise, I might as well go on holiday."

Clijsters returns at a time when the WTA tour is wide open and without a singles player dominating the rankings.

"I am amazed how many players I don't even know," she said. "There are even many names I do not know how to pronounce."

Clijsters, who is married to American basketball player Brian Lynch and gave birth to her daughter Jada last year, is convinced she has the maturity to juggle marriage, motherhood and top tennis.

"Now I have the right balance and I feel good," she said.

Clijsters refused to commit herself beyond the U.S. Open, preferring to make an assessment at that stage. Her career was marred by a series of injuries, including to her hip and back.

"I know a lot, lot more about my body," Clijsters said, adding that she has an exercise regimen designed to prevent injuries.

Earlier, Clijsters had announced she will join Steffi Graf, Andre Agassi and Tim Henman for a series of exhibition matches at Wimbledon on May 17 under the new retractable roof on Centre Court.

She said preparing for the Wimbledon exhibition honed her competitive edge. Soon, she was spotted at the training center putting in long hours.

"I have never trained harder," she said.

Clijsters is also scheduled to play an exhibition June 14 against Michaella Krajicek in the Netherlands, along with two matches for the St. Louis Aces of World Team Tennis in July.